Adapting Science for Students with Visual Impairments

A Handbook for the Classroom Teacher and Teacher of the Visually Impaired

Rosanne Hoffmann, Ph.D.
Project Leader

Elaine Kitchel, M.Ed.
Project Assistant

© 2006

Acknowledgements

Research Assistants
Carol Roderick
Monica Vaught

Graphics & Photography
Bernadette Mudd
Brian P. Dougherty, III

Cover Photo
Ann Travis

Illustrations
Bisig Impact Group

Production Team
Lila Adkins
Anna Fox
Frank Hayden
David Hines
David Manteuffel
Phyllis Williams

Field Consultants
Samir Azer
Linda Bass
Katherine Cooper
Richard Cooper
Sandra Craig
Jamie Dunham
Norma Englehardt
Becky Heck
Kim Huffman
Jan Jasco
Terry Maggiore
Fay Rahni
Karen Richey
Alan Roth
Mark Riccobono
Jimmy Schroeder
Janet Ulwick-Sacca

Adapting Science for Students with Visual Impairments
Copyright © 2006, American Printing House for the Blind, Inc. Louisville, KY 40206-0085
All rights reserved.
Printed in the United States of America
This publication is protected by Copyright and permission should be obtained from the publisher prior to any reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise.

For information regarding permissions, write to

American Printing House for the Blind, Inc.
Resource Services
1839 Frankfort Avenue
Louisville, KY 40206-0085

7-00000-00 Adapting Science for Students with Visual Impairments Handbook

7-00001-00 Adapting Science for Students with Visual Impairments Advance Preparation Checklist

7-00001-00 Adapting Science for Students with Visual Impairments Skills Checklist

Adapting Science for Students with Visual Impairments

A Handbook for the Classroom Teacher and Teacher of the Visually Impaired

Introduction

"It is the supreme art of the teacher to awaken joy
in creative expression and knowledge."

Albert Einstein

This handbook is written for the classroom science teacher who has minimal experience teaching a student who is visually impaired, and resource specialists such as teachers of the visually impaired and paraprofessionals who need supplemental science information. It addresses science laboratory skills at the elementary, middle, and high school levels.

The information and adaptations presented are geared toward students with some usable vision. Please keep in mind that it will not be necessary to use all the adaptations described. Students with any disability are best served when the teacher works with them closely and tailors the learning environment on an individual basis.

Adaptations are also presented for the student who is totally blind with no light perception. These students will benefit most from being encouraged to participate in all activities as much as possible, just like sighted students. A sighted partner may be necessary for some activities and should be chosen with care. Students who are exceptionally good at describing and who like to assist other students in this way make good partners.

This handbook is designed to assist teachers in the full inclusion of their students with visual impairments in science experiences such as laboratory exercises, field trips, and lesson demonstrations. Pedagogical research has shown that all students learn scientific and abstract concepts best when they are active participants, and students who are visually impaired are no exception. Furthermore, the concepts of Universal Design, which foster an inclusive learning environment for students with any type of disability, have helped form the foundation of this handbook.

Throughout this handbook, adapted tools, instruments, and products and the vendors from which they can be purchased will be presented. The abbreviations, addresses, phone numbers, and URLs corresponding to these vendors can be found in the Appendix. An abbreviated list of the same vendors including their abbreviations, names, and phone numbers can be found on the pages preceding both chapters 2 and 4.

Political and social standards demand that APH publications address all individuals. Accordingly, the pronouns "he" and "she" used for male and female students will alternate by chapter.

The information and concepts detailed in this handbook address the National Science Education Standards for grades K-12 in the content area of Science as Inquiry. Content standards NS.K-4.1, NS.5-8.1, and NS.9-12.1 include the following sub-areas:

• Form questions about the natural world
• Devise hypotheses that address those questions, including predictions
• Design experiments to support or refute hypotheses
• Gather data using appropriate devices and measurements
• Interpret data and form conclusions
• Suggest alternative hypotheses to explain data
• Relate data and information to current and new models
• Communicate scientific information

Chapter 1

The Student with a Visual Impairment in the Science Laboratory

This chapter is for individuals without experience in teaching a student with a visual impairment, particularly in a laboratory environment.

Blindness seldom means complete darkness. Rather, it encompasses a range of visual acuity, or sharpness of vision. Blindness includes all poor acuities from 20/200 or worse in the better eye, with maximum correction. Low vision encompasses the range of acuities from 20/70 to 20/200 in the better eye, with maximum correction. Those with a greatly decreased field of view, 20 degrees or less from the center of the visual field, can also be categorized as legally blind, even if the visual acuity is greater than 20/200.

A person who is considered blind may have some light perception, or may be able to detect movement close to the eyes, or may be able to perceive certain colors. Generally, that person's world is an audible and tactile one. The student with blindness will often need special materials to represent visual things in a tactile way. For instance, most blind students will learn to read braille at an early age. Some books are available in recorded and digital forms. Often, raised-line drawings and three-dimensional representations of abstract and intangible objects and concepts are needed.

Most students, however, have some usable vision that enables them to use modifications such as large print, magnifying lenses, text magnification software, telescopes, and other low vision products. The teachers of these students with low vision are those for whom this text was written.

Eye diseases, either individually or together, cause conditions that limit visual acuity, visual fields, or both. Some examples include albinism, cataracts, glaucoma, myopia, optic nerve atrophy, retinitis pigmentosa, and Stargaardt's Disease, to name just a few. To learn more about the causes of visual impairments the reader is referred to another APH publication, Teaching the Student with a Visual Impairment (Gevers & Murphy, 2002).

A student who is visually impaired may have optical devices prescribed by a medical professional. These devices may include:

• magnifiers, designed to enlarge the images of near items,
• telescopes or monoculars, designed for distance viewing, and
• minifiers which augment the field of view for those with poor peripheral vision.

It is important that the student use the prescribed optical devices, particularly in the science laboratory where issues of safety are paramount.

Students with visual impairments do not necessarily learn differently than students with normal vision. A common misconception is that the student with a visual impairment cannot be a visual learner. The fact is that all students, visually impaired or not, learn using multiple sensory pathways with one path usually dominating. For example, Sylvia may be primarily an auditory learner, but could use visual and tactile cues as well to help reinforce what she is experiencing via hearing.

Technological advances such as CCTV, an acronym for closed-circuit television, and text-to-speech computer software have made vision-based lessons more accessible to the student who is visually impaired. Nevertheless, the student with a visual impairment will benefit from simple accommodations and lessons presented in multiple formats. Care should be taken to ensure that all pertinent materials are accessible. This includes measuring devices, charts, reading materials, and equipment. Ways to do this include increasing the font size of written materials, using raised-line indicator marks, and ensuring compatibility of the activity with the use of an optical device recommended by the student's vision clinician. Chapter 4 has specific information that addresses the issue of accessibility.

A meeting before the school year or semester actually starts, in which the instructor becomes familiar with the student's visual impairment and the student is introduced to upcoming activities and required skills, is highly recommended. The Advance Preparation Checklist and Skills Checklist provided at the end of this book are designed to facilitate this process. Materials that are needed in alternative formats, such as large print, braille, or audio, should be ordered well before the class begins. During class or lab sessions, it is recommended that the instructor clearly explain visual images as they are presented, or before if necessary, and provide actual objects such as beakers and flasks for tactile exploration. Anything the teacher writes on the board should be read aloud.

Material presented on the overhead projector may be invisible to the student with a visual impairment. Commercially prepared transparencies often have text that is too small and images that are too complex and pale. Handmade images are better, and teachers need to take the time to make the images and text very large and bold. Ask the student if the projected images for a particular lesson are visible to her.

A characteristic of low vision that confounds those trying to provide accommodations is its variability. This means that a student's vision can be better or worse depending upon the time of day, fatigue level, or state of mind. These variations in performance can be minimized by ensuring that the student with a visual impairment is seated at the best possible location for her vision, such as the front or the side of the room, and out of the way of excess traffic and distractions. It might be necessary to have an alternate seat with access to a computer and/or CCTV.

Lighting is another important issue. The quality of the light source is often more critical than the amount of light. Sunlight shining toward a student's face, monitors with blue screens, and fluorescent lighting are sources of stressful levels of high frequency, short-wavelength light and glare. These light sources are fatiguing and can lead to eyestrain, thus reducing stamina and detracting from the student's ability to see clearly for a long period of time.

The student's seat should be positioned so that any natural sunlight shines from behind her in order to reduce glare and prevent eyestrain. An exception to this rule is if the student is seated at the computer. Sunlight should not shine on the computer screen because it causes glare from the surface of the monitor. Instead, try to seat the student at right angles to the sun.

Warm incandescent light with a predominance of long wavelengths is preferable to cool white fluorescent light. If changing the existing fluorescent light bulbs or tubes in a laboratory or classroom from cool white to warm white is not possible, try lighting the student's work area with a task lamp fitted with an incandescent bulb. As another option, specially-colored filters in the form of wrap-around sunglasses can be used. The color chosen should be overseen by an optical clinician and selected so that glare is minimized and contrast maximized. This will vary from student to student, according to eye condition. A selection of colored filters are available from:

NoIR Medical Technologies

P.O. Box 159
South Lyon, MI 48178
Phone: 800-521-9746
FAX 734-769-1708

The student with a visual impairment in the science laboratory is best helped by recognizing her individualized needs and accessing the resources available to her and the teaching institution. If the student meets the criteria for visual impairment and is enrolled in a public or private K-12 educational program, she is eligible for registration in the Federal Quota Program. This means that a set amount of money per registered student is reserved for the purchase of educational materials produced by the American Printing House for the Blind (APH). These funds can be accessed by communicating with the appropriate state designated Ex Officio Trustee by visiting the website (www.aph.org), or calling the toll free number (1-800-223-1839).

Abbreviated List of Vendors
APH	American Printing House for the Blind	1-800-223-1839
AM	Ann Morris	1-800-537-2118
BAS	Bel-Art Scienceware	1-800-423-5278
CB	Carolina Biological	1-800-334-5551
DE	Delta Education	1-800-258-1302
DL	Dynamic Living	1-800-940-0605
ES	Edmund Scientific	no phone listed
FLN	Flinn Scientific	1-800-452-1261
FRE	Frey Scientific	1-800-225-3739
HP	Howe Press	1-617-972-7308
ILA	Independent Living Aids	1-800-537-2118
LHS	Lawrence Hall of Science	1-510-642-8941
LSI	Laboratory Safety Institute	1-508-647-1900
LS&S	Products for Visually Impaired and Hard of Hearing	1-800-468-4789
MA	MaxiAids	1-800-522-6294
NFB	National Federation of the Blind	1-410-659-9314
RNIB	Royal National Institute for the Blind	no phone listed
SC	SightConnection	1-800-458-4888
SK	Science Kit & Boreal Laboratories	1-800-828-7777
SW	Sargent-Welch	1-800-727-4368
VER	Vernier Software & Technology	1-888-837-6437
WNS	Ward's Natural Science	1-800-962-2660

Chapter 2

Safety in the Science Laboratory or Classroom

Safety in the Science Laboratory or Classroom

Many potential hazards exist in the science classroom and/or laboratory. Generally, the teacher is responsible for the proper and safe use of instruments and supplies as well as the condition of the teaching setting. Even so, safeguards to prevent accidents can be integrated into the curriculum, thus shifting some of the responsibility to the students and raising their awareness. For example, students can rotate as safety officers and conduct inspections of particular areas on a regular basis. Students can also become involved by preparing posters or signs, which alert people who enter the room or laboratory to safety issues. Students need to understand the importance of following directions. They should ask their instructor for permission before they begin an experimental protocol.

General Safety

Visually impaired or not, some students are more vulnerable to safety hazards than others. A few reminders will make the classroom and laboratory safer for everyone. Aisles must be open and exits clearly marked. Chairs should be pushed under tables or desks when not in use, and not left in the aisles. Electric cords need to be properly maintained and situated so they do not pose potential electrical or tripping hazards. Room evacuation procedures should be practiced.

The student with a visual impairment performs best in familiar territory. For this reason, the layout of the room and all its special features must be specifically shown to him, preferably before the first class meeting. Likewise, these students must be informed of any changes in the arrangement of the classroom, laboratory, equipment, or supplies whenever they occur.

The seat or lab station for a student who is visually impaired must be chosen with care. Attention to elements such as lighting and accessibility to a computer or other technological accommodations will sometimes be necessary. Access to demonstration materials may require an aisle, a front seat, or magnification through optical means. It is always a good idea to ask your student what he needs.

All students and instructors need to know the location of the fire extinguisher, eye-wash, safety shower, first aid kit, fire alarm pull, and any other safety apparatus in the room. Periodic inspections of safety devices at regular intervals by the school administration, science instructors, or students are highly recommended. If the room is fitted with gas lines for Bunsen burners, regular inspections for leaks should be scheduled. Students need to be informed of the location of specialized waste receptacles used exclusively for glass, preserved animal tissue, and regular trash. Liquid wastes need to be handled carefully with separate containers for acids, bases, and organics. Ideally, these containers should not be stored near each other nor on the floor. Concentrated acids and bases are always diluted by adding the concentrate to water, never the reverse.

Personal Safety

When engaging in science activities, students should dress simply. Ties, scarves, loose fitting clothing, excessive jewelry, as well as open-toed shoes and sandals without socks are inappropriate attire. Long hair should be tied back. It is not recommended that students wear contact lenses, since chemicals can diffuse underneath them and cause discomfort or irritation. Canes should be hung near the door of the laboratory or classroom in order to prevent tripping hazards.

Eating, drinking, and chewing gum in the science classroom or laboratory are inappropriate and potentially dangerous activities. Along the same line, students should be advised never to taste chemicals.

Safety Attire

Students must have access to and be required to wear safety attire when appropriate, including goggles, aprons, and gloves as shown in Figure 2.1. Goggles in particular should be chosen with care in order to protect all students, but especially those with a visual impairment, such as total blindness in one eye and limited sight in the other. The following factors need to be taken into consideration when selecting goggles: area of coverage, anti-fog protection, splash protection, and whether they are shatterproof. Gloves need to be chosen according to the protection required. Heat resistant Kevlar® gloves are available from CB, as are waterproof and chemical resistant latex or vinyl rubber gloves. The latter can also be found at discount stores. Plastic, Tyvek®, and rubberized aprons are also available from CB. More information about safety and appropriate laboratory attire can be found at:

The Laboratory Safety Institute
192 Worcester Road
Natick, MA 01760-2252
1-800-647-1977
www.labsafety.org

Figure 2.1

Student wearing appropriate safety attire including goggles, apron, and gloves.

Chemicals

Labels

All solid and liquid chemicals must be in proper containers with legible large print and braille labels and located in a specific area of the room such as a reagent shelf or cabinet. Cabinets and shelves should also be labeled to help keep things organized. High-contrast labels prepared with large boldface black letters on a white or yellow background best accommodate the student with low vision or legal blindness. Labels can be prepared with labeling or masking tape and Sharpie markers from CB. 20/20 markers are also available from APH. Braille labels embossed on labeling tape can be made with a 3M Braille Labeler available from ILA, SC, MA, and NFB. This device is made so that braille knowledge is not needed to prepare the labels. Care should be taken not to apply braille labels upside down. Hazardous chemicals can be further identified with a piece of sandpaper glued near the label, thus alerting the student who is blind.

It's handy to have a balance or scale and volume measuring lab ware near the chemical shelf or cabinet. This way, students won't have to walk long distances with a chemical in order to get what they need for an activity. Students should keep their fingers away from their eyes when handling chemicals and always wash their hands after using them.

Fume Hood

Some science laboratories come equipped with a fume hood that has a continuous flow of air up and out through a vent in the building, as shown in Figure 2.2. This device expels fumes, thus allowing students to handle noxious and volatile chemicals, such as hydrochloric acid, without fear of inhalation. All students should know the location of the fume hood and use it whenever indicated.

Figure 2.2

Student handling a chemical in the fume hood, preventing fumes from getting near his face.

Making a Solution

A solution is composed of a solvent (such as water) and a solute (such as sodium chloride) mixed together so that the solid is dissolved in the liquid. Or, a solution can be prepared by mixing two liquids together such as alcohol and water.

As a rule of thumb, when mixing a chemical with water, the chemical is always added to the water. Water is never added to a chemical, especially if the chemical is an acid or a base. Addition of even small amounts of water to acid or base can result in sputtering of the liquids and burn injuries to one or more students.

The final volume of the solution must take into account the volumes of both the solute and solvent, even if the solute is in a solid powder form such as sodium chloride (NaCl) or sugar (sucrose). See chapter 4 for measuring methods and their adaptations, and use the following procedure to make a solution correctly:

• Measure out the water or solvent close to, but less than, the final volume desired, and pour it into a container large enough to hold both substances.
• Weigh or pour out the solute or chemical to be added to the water.
• Add the solute and stir it into the solvent until it is completely dissolved.
• Add more water or solvent until the final, desired volume is reached; this may require measuring the final volume in a graduated cylinder for accuracy.

Wafting Chemicals

Sometimes it is necessary to smell a liquid or solid chemical in order to identify or characterize it, but this can be hazardous if done improperly. A chemical should never be inhaled with the nose directly over an open container. Rather, the chemical should be held a short distance away and the hand waved over the open container and toward the student's nose. This action will allow the student to waft a minute amount of the substance rather than inhaling large amounts of it.

MSDSs

All chemicals, no matter how benign, must have an accompanying Material Safety Data Sheet (MSDS) when they enter the classroom or laboratory. All distributors are required to include the appropriate MSDS with any shipment containing a chemical. The MSDS describes the composition and potential hazards of the chemical, as well as how to deal with situations such as accidental ingestion, skin or eye contamination, and spills. MSDSs are easily accessible if they are kept in a folder or binder in the classroom or laboratory. Students need to know where the binder is kept, and if its place in the laboratory changes. A magnifier should always be stored with it.

Figure 2.3

Sample MSDS form showing specific safety information.

Printed MSDSs vary in format, which means that the font size can be small or difficult to read. The student with low vision or legal blindness might need the help of a magnifier or sighted person to actually read a particular MSDS. Alternatively, MSDSs can be accessed and viewed for free at many different websites. For example, MSDS-SEARCH houses the National MSDS Repository, which can be accessed at www.msdssearch.com. On-line MSDSs are presented in different formats, depending upon the manufacturer of the chemical. For example, Mallinckrodt provides MSDSs as html (hypertext markup language) files. Users can enlarge the text in html files with the "View" menu of their internet browser if necessary, and screen-reading software such as JAWS can make these files accessible to visually impaired students who are not print readers. Other manufacturers present MSDSs as PDF (portable document format) files. These files can be enlarged with the zoom feature on the browser toolbar. At the present time, screen-reading software cannot interpret all PDF files, making some inaccessible to visually impaired students who are not print readers. On the other hand, if the MSDS of a chemical from a particular vendor is presented as a PDF file and cannot be accessed, it may be possible to find an MSDS for the same chemical from another vendor in html format. Difficulties will arise if the screen-reading software cannot interpret chemical symbols and mathematical notations. In these cases, the MSDS will have to be read to the visually impaired student who is not a print reader.

Lab Ware

Plastic lab ware is unlikely to break and thus the safest option for all students. Plastic beakers, bottles, graduated cylinders, and flasks are available from many vendors such as CB, ES, and LHS. On the other hand, plastic is lightweight compared to glass, making tall plastic objects like graduated cylinders prone to over-tipping. Some plastic graduated cylinders come with sturdy square-shaped bases that counter this tendency. Tall cylinders can be stabilized with a clamp secured to a support stand, if necessary as shown in Figure 2.4. If students are made aware of the differences between glass and plastic lab ware, many potential accidents can be avoided.

Figure 2.4

Glass graduated cylinder, clamped on support stand for stability.

If the lab ware in the classroom or laboratory is available only in glass, use intact containers with no cracks or chips, especially if they will be heated.

Some chemicals, such as concentrated hydrochloric acid, can be stored only in glass containers. If there is any question regarding the safe handling of any chemical or its proper container, consult the MSDS for that specific chemical.

Electrical Hazards

• Electrical cords, plugs, and outlets should be in good repair.
• Use electrical devices away from water and other liquids.
• Unplug electrical devices with the plug, not the cord.
• Electrical cords should be located so that they are not a tripping hazard.

Temperature Hazards

• Hot plates need time to cool before it's safe to touch them.
• Use care and follow directions when using a Bunsen burner; see chapter 4.
• Dry ice should not be touched with bare hands, since this presents a potential "burning" hazard.
• Never heat liquid in a container to the point that all the liquid has evaporated and caused the container to boil dry. Never use a cracked or chipped receptacle to contain a substance to be heated.
• When heating a test tube in the flame of a Bunsen burner, always use a test tube holder, available from CB. The test tube should be tilted away from the person holding it and away from any other students.

Mechanical Hazards

• Sharp instruments such as scissors, scalpels, and pointed forceps must be kept in appropriate containers.
• Projectiles and moving objects such as pendulums and cars are a potential hazard for students who are visually impaired.

Chapter 3

Scientific Method and Experimental Design

"The whole of science is nothing more than a refinement of everyday thinking."
Albert Einstein

"The greatest discoveries have come from people who have looked at a standard situation and seen it differently."
Ira Erwin

"Creativity involves breaking out of established patterns in order to look at things in a different way."
Edward de Bono

Science and the Scientific Method

"Science" is an umbrella term that embraces content areas such as biology, chemistry, physics, and geology and all their interrelated branches. Put this way, science can be thought of as just a collection of facts, but it's also a way of thinking. Science is a logical process that helps explain ordinary and even extraordinary events and observations in the natural world. This often results from insightful and creative ways of looking at things. The "scientific method" is a reasoning process that follows a number of simple rules.

The scientific method can be applied to any field of study, and as in science, the process is the same. For example, the observation could be made that William Shakespeare wrote all of his works in the English language. From there, one could ask why, and then hypothesize that English was the native and only language of Shakespeare. Research on the topic would reveal that although English was Shakespeare's native language, he was well schooled and fluent in Latin. This discovery does not support the original hypothesis. A revised or alternative hypothesis might suggest that English was the only language of his intended audience, and so on.

Hypothesis Formation

From the example above, it is clear that observations not only provide information, but are also the springboards from which questions arise. A hypothesis is an educated guess, which must be testable, at least in theory. Hypotheses can be informed by observations, previous knowledge, insight, and additional information obtained by research.

The formulation of the hypothesis as an "if...then..." statement creates an experimental set-up with a predicted outcome. Here's an example: "If Shakespeare spoke only English, then all of his works would be composed in English." Research into the life of Shakespeare tests this hypothesis, the results of which would either support or refute its plausibility.

Sometimes, hypotheses cannot be tested directly due to limitations in technology. In these cases, observations and "data" need to be inferred. In the Shakespeare example above, time travel is not possible, so written accounts of 16th century English history must be used to test the hypothesis.

A common misconception is that hypotheses can be "proven." In reality, a hypothesis can be either supported or not supported by the results of one or many tests. A single experiment can topple the most elegant explanation for a particular phenomenon. For example, the earth was once thought to be flat because ships and other objects seemed to drop off over the horizon. Magellan's successful expedition around the world in the early 1500s provided conclusive evidence against this hypothesis. When the technology for space travel arrived in the 1960s, pictures of the earth from outer space further confirmed its round shape.

The basic steps of the scientific method using another example are as follows:

1. Observation and question: "Why doesn't my flashlight work?"

2. Hypothesis: "Maybe the batteries are dead."

3. If...then...formulation: "If I change the batteries, then my flashlight will work"

4. Test hypothesis: Switch the old batteries for new ones. Turn on the flashlight.

5. Obtain and interpret results: If the flashlight lights up, the hypothesis is supported. If the flashlight still does not light up, an alternative hypothesis must be devised and tested.

Experimental Design

Science, regardless of discipline, is empirical. This means that valid conclusions and data can be derived only from events or parameters that are observable. Consequently, experimental data and observations must be described or measured in some way as described in chapter 4. Furthermore, reliable data are those that can be reproduced by one or more observers under specified conditions.

A well-designed science experiment is one that is "controlled." This means that the experimenter compares the effects of one or more test treatments to those of the original or "control" conditions. If there is more than one test treatment, separate groups are set up to determine the treatment effects individually. The experimental set-up and the appropriate methods selected for data collection depend upon what needs to be measured or described. Finally, experiments must be repeated to eliminate the possibility that the results are just chance events. Consistent results after several repetitions are also an indication of good technique. A summary of the basic steps follows:

• Determine control and test treatments
• Identify dependent and independent variables (see below)
• Choose method(s) for data collection
• Perform experiment and obtain data
• Repeat experiment

Treatments and their effects are often called "variables." In every experiment, the independent variable is governed or determined by the experimenter and is otherwise known as the treatment or cause. The dependent variable is the measured or observed effect of the treatment. Correct identification of the variables within control and experimental groups will help with data presentation and interpretation, as shown in Table 3.1.

Table 3.1

Hypothesis 1: If I change the batteries, then my flashlight will work.
Independent Variable	Dependent Variable (does it work?)
Control treatment (use old batteries)	NO
Experimental treatment (use new batteries)	NO
Hypothesis 2: If I change the light bulb, then my flashlight will work.
Independent Variable	Dependent Variable (does it work?)
Control treatment (use the old light bulb)	NO
Experimental treatment (use new light bulb)	YES

In the flashlight example given, the control is the flashlight in its non-working condition with "old" batteries, whereas the first experimental treatment is replacing the old batteries with new ones. The independent variable is a change in some aspect of the flashlight, such as the battery. The effect of that change, that is, whether the flashlight works or not, is the dependent variable. Both of these variables would be determined for the control and the experimental treatments.

If the experiment does not support the first hypothesis, an alternative plan is devised. A new hypothesis in this example could be, "if the light bulb is changed, then the flashlight will work." In this case, the independent variable is the status of the light bulb (old or new) and the dependent variable is still whether the flashlight works. It's important to change only one independent variable at a time, e.g., the batteries OR the light bulb.

When the student with a visual impairment uses the scientific method of inquiry, or performs any other science activity, care should be taken so that all pertinent materials are accessible. This includes measuring devices, charts, reading materials, and equipment. Ways to do this include increasing the font size of written materials, using raised-line indicator marks, and ensuring compatibility of the activity with the use of a magnification device recommended by the student's vision clinician. See chapters 4, 5, and 6 for information about measurement, data collection, and presentation. Use the checklists at the end of this handbook to determine and meet the individual needs of the student prior to entering the science laboratory.

Abbreviated List of Vendors
APH	American Printing House for the Blind	1-800-223-1839
AM	Ann Morris	1-800-537-2118
BAS	Bel-Art Scienceware	1-800-423-5278
CB	Carolina Biological	1-800-334-5551
DE	Delta Education	1-800-258-1302
DL	Dynamic Living	1-800-940-0605
ES	Edmund Scientific	no phone listed
FLN	Flinn Scientific	1-800-452-1261
FRE	Frey Scientific	1-800-225-3739
HP	Howe Press	1-617-972-7308
ILA	Independent Living Aids	1-800-537-2118
LHS	Lawrence Hall of Science	1-510-642-8941
LSI	Laboratory Safety Institute	1-508-647-1900
LS&S	Products for Visually Impaired and Hard of Hearing	1-800-468-4789
MA	MaxiAids	1-800-522-6294
NFB	National Federation of the Blind	1-410-659-9314
RNIB	Royal National Institute for the Blind	no phone listed
SC	SightConnection	1-800-458-4888
SK	Science Kit & Boreal Laboratories	1-800-828-7777
SW	Sargent-Welch	1-800-727-4368
VER	Vernier Software & Technology	1-888-837-6437
WNS	Ward's Natural Science	1-800-962-2660

Chapter 4

Using Scientific Equipment:

Adaptations for the Science Student with a Visual Impairment

"Discovery favors the well-prepared mind."
Thomas Edison

THE MICROSCOPE

Of all the magnifying instruments, the compound microscope and the stereomicroscope are the most useful in the laboratory. Microscopes are precise and expensive instruments and need to be handled with great care. It is strongly recommended that the instructions included with a particular microscope are followed.

A description of the parts of the microscope follows. Note that braille labels can be affixed to the corresponding parts, allowing the student who is blind to learn how the microscope functions. Braille labels embossed on labeling tape can be made with a 3M Braille Labeler available from ILA, SC, MA, and NFB. This device is made so that braille knowledge is not needed to prepare the labels. Care should be taken not to apply braille labels upside down.

The compound microscope, as shown in Figure 4.1, works with an ocular lens and a set of objective lenses. The ocular lens is closest to the eyes and usually has a magnifying power of 10x. The objective lenses are closest to the object being viewed. Three or four objective lenses, ranging in power from 4x to 100x, are mounted on a revolving nosepiece and click into place one at a time. The total magnification of a specimen, calculated by multiplying the ocular lens magnification by the magnification power of the objective lens, usually ranges from 40x to 1000x.

Figure 4.1

Compound Microscope
The compound microscope with the following parts labeled: ocular lens, body tube, coarse-adjustment knob, fine-adjustment knob, arm, inclination point, base, light source, diaphragm, condenser lens, stage, objective lens, revolving nosepiece.

The compound microscope is used to view very tiny and transparent objects not ordinarily visible to the unaided human eye, such as ultra-thin slices of plant and animal tissues or individual mineral crystals. The limit of resolution, or the ability of the human eye to discriminate between two adjacent objects, is about one-tenth of a millimeter, which is about the thickness of a human hair. The resolving power of the compound microscope ranges from 1 millimeter (millimeter), or 1 one-thousandth of a meter, to 1 micron (µ), or 1 millionth of a meter. It helps to put these units into perspective by noting that a frog egg is a little bit bigger than 1 millimeter in diameter, a human hair can be from 60 to 120 microns thick, and most plant and animal cells are from 10 to 100 microns in diameter.

The student who is blind can remain engaged during laboratories that involve the microscope in the following ways:

• Learn the parts of the microscope
• Determine the orientation of the image as a result of magnification (up-side-down and backwards)
• Understand the concept of scale using the metric system by developing a model of sequential size changes; e.g., compare 4x to 10x to 100x, etc.
• Prepare and study tactile diagrams of images viewed under the microscope
• Understand what is actually visible by magnification; e.g., which organelles of the cell are visible with the compound microscope? For example, the nucleus of some cell types is visible via differences in contrast, but staining techniques make it much more apparent; chloroplasts in many plant cells are visible because they are green.

Points to remember when using the compound microscope include:

• Carry the microscope with two hands, using one to hold the microscope arm and the other hand to provide support from underneath the base, as shown in Figure 4.2.

Figure 4.2

Proper microscope handling with two hands; the student is holding the microscope arm with one hand and providing support from underneath the base with the other hand.

• The light source should be turned off at all times except during use. This will increase the life span of the light bulb, and battery, if present. Always turn off the light before unplugging the microscope and placing it in its storage area.
• All microscope lenses must be cleaned with lens paper specially made for this purpose. Other types of paper and cleaners can be abrasive and scratch the soft optical glass.
• After placing a prepared slide on the microscope stage, always begin viewing with the lowest power objective (usually 4x or 10x) raised to its highest point above the slide using the coarse adjustment knob. Then, use the same knob to move the objective lens as close as possible to the specimen, but do this while viewing the microscope from the side so as not to damage the glass slide. View the specimen through the ocular lens, and slowly raise the coarse adjustment knob and bring the image into focus. Use the fine adjustment knob for a sharper image. Click the next highest magnification objective lens into place for a more detailed view; this will be accompanied by a decrease in the field of view. Sharpen the image with the fine focus knob if necessary.
• To prevent eyestrain, keep both eyes open when viewing an image through a compound microscope with one ocular lens. This viewing technique takes practice, and students with low vision may need to occlude the non-viewing eye with one hand or an occluder available from APH. Alternatively, an old pair of sunglasses can be modified by popping out the lenses and replacing one side with an opaque sheet of material such as cardboard.
• Before returning the microscope to its storage area, turn the light source off, raise the coarse adjustment to its highest point, remove the last slide, click the lowest power objective into place, and put on the protective cover.

Some compound microscopes have two ocular lenses and are therefore binocular. In this case, viewing specimens is simpler because both eyes are open and working, obviating the need to deal with potential eyestrain issues.

The stereomicroscope, as shown in Figure 4.3, also known as a dissecting microscope, is used for viewing the details of large, whole, and sometimes opaque specimens, such as a flower, a rock, or a frog dissection. Since the optics of this instrument are stereoscopic, the specimen in view always looks three dimensional. The stereomicroscope has two ocular lenses, usually at 10x magnification, that work in combination with objective lenses ranging from 1x-4x. The range of magnification is therefore from 10x to 40x. Coarse adjustment is sufficient to focus on the specimen, which usually does not require any special preparation other than placement on the viewing stage. The stereomicroscope should be used with the same precautions and care as the compound microscope.

Figure 4.3

Stereomicroscope
The stereomicroscope with the following parts labeled: ocular lenses, objective lenses, stage, and focusing knob.

Videomicroscopy

Significant advances have been made with instructional technology, and microscopy is no exception. Microvideo or CCD (charged coupled device) cameras are available which allow an image to be displayed on a TV monitor or computer screen, as in CCTV (closed circuit television). This greatly enlarges the image, which helps many students with low vision, and allows the lesson to be presented to more than one student at a time.

CB offers many options for CCD cameras of varying resolutions that will present images of macroscopic or large specimens such as leaves, rocks, and insects, as shown in Figure 4.4.

Figure 4.4

Videomicroscopy
Microvideo CCD camera attached to a flexible gooseneck wand, allowing the display of an image of plant leaves on the computer screen.

The ClearOne^® FlexCam^TM desktop microvideo camera displays images on a TV or video monitor, which can be recorded with a VCR or video-compatible personal computer (PC). The ClearOne^® FlexCam iCam digital camera displays images on a computer screen, and captures and manipulates them using the accompanying computer software. Both camera models can be fitted with adapters, which attach the camera to the microscope and allow microscopic images to be displayed on a TV monitor or computer screen, as shown in Figure 4.5. Camera packages typically come with a camera stand and flexible gooseneck wand, microscope adapter, and all required cables. Other packages also include a compound microscope. To add a CCD camera to an existing microscopy set-up, call the vendor to ensure that their adapters will fit that particular microscope type.

Figure 4.5

Videomicroscopy
Microvideo CCD camera attached to the body tube of the compound microscope via an adaptor, displaying an image of plant cells on the screen of a video monitor.

Specimen Preparation

Stereomicroscope

A minimum of preparation is required for specimens viewed on the stage of the stereomicroscope. Items ranging from crystals, rocks, whole leaves, insects, and small animal dissections may be studied in this manner. The specimen need only be immobile, placed on the stage, and brought into focus using the focusing knob. Some microscopes come with removable stages that can be flipped over to provide different contrasting backgrounds. Aquatic specimens such as seaweed, algae, small worms, water fleas, and fish and amphibian eggs can be suspended in water in a small transparent glass or plastic dish, such as the bottom or top of a Petri dish.

Compound Microscope

Specimens must be mounted on glass slides and covered with a coverslip in order to be viewed with the compound microscope. This means they have to be very small and transparent. Some visually impaired students will require the assistance of a stand magnifier, available from CB or SP, in order to prepare slides.

Wet Mounts

Many specimens are prepared for the compound microscope as wet mounts. These consist of a whole organism, such as a water flea, or a piece of seaweed, sandwiched with water between the glass slide and a glass coverslip. Step by step instructions follow as shown in Figure 4.6:

Figure 4.6

How to prepare a wet mount without air bubbles:
Place specimen on clean glass slide.
Cover specimen with a drop of water.
Place coverslip on glass slide so that one edge makes contact with the water droplet.
Allow the coverslip to drop into place.

• Place the specimen on a clean glass slide with a tweezer or pair of forceps.
• Cover the specimen with a small drop of water using an eyedropper or small pipet.
• Hold the coverslip with forceps or fingertips and place it on the glass slide so that one edge of the coverslip is making contact with the water droplet.
• Release the grasp of the forceps or fingers and allow the cover slip to drop into place.
• Note: The coverslip must make contact with the drop of water BEFORE it is dropped into place to prevent the formation of air bubbles between the slide and the coverslip.
• To examine pond water or organisms suspended in fresh or seawater, simply place a small drop on the slide and cover it with the coverslip using the instructions above.
• Never view a slide under the compound microscope without a coverslip.

Deep-Well Slides

A simpler method of preparing small specimen slides for viewing under the compound microscope, stereomicroscope, or overhead projector involves the use of a Deep-Well Slide, available from CB as shown in Figure 4.7. This item consists of a square shaped, clear plastic slide, with a 2.5 centimeter round well in the center. Place the specimen in the center of the well, cover it with water using a small pipet or eyedropper, and snap on the fitted cover. This preparation is less likely to form air bubbles or dry out, and is easier for students to manage, both physically and visually.

Figure 4.7

Carolina Deep-Well Slides
Remove the cover.
Add the specimen with water if necessary.
Replace the cover.

Permanent Slides

The preparation of permanently mounted, thin sections of large or thick specimens requires techniques beyond the scope of this book. Commercially prepared, permanent slides of all types can be purchased from CB and other science vendors.

DISSECTIONS

Many science classes include dissections of whole organisms as part of the study of plants, animals, and fungi. Preserved and live organisms are available from CB, and fresh plant material, flowers, and mushrooms are available from the grocery and/or garden center. Students need to be aware that dissecting instruments are sharp and should not be brought close to the eyes for identification. Students need to keep their fingers away from their face and eyes, especially after touching preserved organisms.

Adaptations and resources that can help the student who is visually impaired perform dissections include:

• stand magnifier; available from CB, AM, DL, FRE, ILA and WNS
• dissecting microscope
• CCTV
• models with or without removable parts available from CB
• Virtual Dissection Software; CB offers many programs for a variety of organisms such as Digital Frog 2: www.digitalfrog.com/products/frog.html

QUANTITATIVE MEASUREMENTS

Measurements for scientific studies are always made using the metric based International System of Units (ISU). The Imperial system, which uses inches, feet, yards, pounds, ounces, etc., is not appropriate and seldom used. An Imperial-Metric conversion table is included in this handbook at the end of this chapter.

Accessible Calculators

• Talking calculators with large numeral displays are available from AM, LS&S, MA, DL, and ILA.
• Accessible Graphing Calculator is a software program available from ILA and AM. It is a self-voiced talking program that performs all the functions of a scientific graphing calculator and is continuously upgraded.

The International System of Units

The ISU is a base 10 system, which means that units are expressed in multiples and fractions of 10 as indicated by the prefixes before each unit. Conversion of units into multiples and fractions of each other is achieved by simply moving the decimal point and changing the prefix of the particular unit. Table 4.1 shows various physical properties and the most commonly used units to measure them in the first two columns. The corresponding symbols or abbreviations and the multiplication factor used to derive the units with prefixes are shown in the third and fourth columns. Standard SI units*, or those that have not been multiplied or divided by a factor of 10, are shown in bold.

Ordinary measuring instruments can present a challenge to a student with a visual impairment. Accommodations and specialized equipment for making all kinds of measurements are presented in this chapter following Table 4.1. Please refer to the Appendix and the abbreviated list of vendors at the beginning of this chapter for sources of specialized equipment and devices.

Table 4.1
Common Units of Measurement from the International System of Units
[Standard SI Units* in Bold]

Physical Property	Unit	Symbol	Standard Unit Multiplication Factor
Length	kilometer	km	1000
	meter	m	~
	centimeter	cm	0.01 or 10-2
	millimeter	mm	0.001 or 10-3
Mass	kilogram	kg	1000
	gram	g	~
	milligram	mg	0.001 or 10-3
Time	second	s	~
Temperature	degrees (Celsius)	° C	~
Volume	liter	l	~
	milliliter	ml	0.001 or 10-3
	microliter	µl	0.000001 or 10-6
Force	newton	N(kg·m/s2)	~
Energy	Joule	J	~
	kilojoule	kJ	1000
Pressure	pascal	Pa	~

* Note: The standard SI units presented here are not to be confused with Base SI units, which are different in some cases; e.g., kg for mass.

LENGTH

Length is the simple measurement of how long something is in one dimension, such as height, width, breadth, or distance traveled. Length measurements can also be used to calculate derived properties such as area (length times width), volume (length times width times breadth), and speed (distance traveled divided by time).

Length Measuring Devices and Adaptations

Meter Tapes and Rulers

The following adapted devices have large print and/or braille numbers with raised-line increments.

• LHS sells a large print, tactile, braille meter tape
• APH offers a variety of measuring tools:
  
  -- Large print, braille toss-away 7 inch/18 centimeter ruler
  
  -- One-foot metric and inch braille ruler
  
  -- 30 centimeter large type, braille flexible ruler
  
  -- Braille meterstick
• MA and DL sell a battery operated talking tape measure that announces length in metric units.

Ordinary rulers or measuring tapes can be made tactile or more visible by affixing one of the following materials at the centimeter or half-centimeter marks.

• Hi-Marks Fluorescent Marking Liquid; available from LS&S
• White glue
• Staples
• Glue gun with wax sticks

String

A piece of string can be used to measure lengths or distances difficult to manage with a measuring tape or rigid ruler. The string can then be measured accurately with a tactile or large print ruler.

Trundle Wheel

Distances on the floor or ground can be measured with a Trundle Wheel, available from CB. This device rolls directly on the floor and makes a clicking sound at one-meter intervals in both the forward and backward directions; see Figure 4.8.

Figure 4.8

Trundle Wheel
The trundle wheel is pushed along the floor via an attached handle.
The wheel clicks after every one-meter revolution.

Counting Footsteps

Distances on the floor or ground can be measured by counting footsteps placed toe to heel after measuring the length of the foot from toe to heel.

MASS

Mass is defined as the amount of a particular substance or matter present and is measured in grams (g). This skill is required to determine the mass of an object, for the preparation of solutions, and for density calculations. Density is defined as the mass of a substance divided by its volume and is expressed as grams per unit volume (grams/centimeter³ or grams/milliliter). Mass measurements can also be part of an experimental procedure such as charting an animal's growth by weighing or "massing" it over a period of time, or calculating the force of a moving object (force equals mass multiplied by the acceleration; F = m · a).

Note that mass and weight are not the same. Mass refers to the amount of matter present and is actually a measure of an object's inertia. Inertia describes an object's resistance to changes in its state of motion or non-motion. An object with a lot of inertia, such as an elephant, has a lot of mass. Alternatively, a feather does not have much inertia and consequently, not much mass.

On the other hand, weight is a force because it takes into account both the mass of an object and the force of attraction of that object to the earth, or gravity. Scientists measure the force known as weight in newtons (kilograms × m/s², see Table 1 above), but many of us are more familiar with the Imperial units "pounds" and "ounces."

Mass Measuring Devices and Adaptations

Balances and Scales

• LHS offers the SAVI/SELPH double "cup" balance adapted for use by students who are blind or with low vision. This balance is geared for the elementary grades, but it's perfectly usable by upper level students. Note that objects or substances can be weighed or massed only to the nearest gram. The mass of the object placed in one cup is counterbalanced by standard mass pieces added to the second cup as needed. Or, if a specific amount of a substance is needed, that amount in gram pieces is placed in one cup, and the substance is added to the second cup. In either case, when the object or substance and mass pieces are perfectly balanced, it can be detected with the tactile indicator, as shown in Figure 4.9.

Figure 4.9

SAVI/SELPH Balance
Modified balance consists of a plastic bar with holes for two removable cups and a tactile balance-indicator. Cups for objects and standard mass pieces are removable.

• CB and other science vendors offer a triple beam balance that can be adapted for students who are visually impaired. APH has tested the Ohaus model number ER-70-2150 available from CB. Etch marks made with a triangular file on the single gram scale on the front-most beam is the only modification required. The middle and back beams of these kinds of balances are already notched, so the student can feel and count the number of marks corresponding to the places to which the riders should be moved on all three beams. When the three riders have been properly adjusted to counterbalance the item placed in the pan, the pointer will rest quietly at the zero mark, which might need to be etched as well. The student can move the riders with one hand while feeling for the balance point with the other hand, as shown in Figure 4.10.

Figure 4.10

Triple Beam Balance
Student massing an apple on pan of triple beam balance. The gram marks on the front beam are etched, so they can be felt by the student who is visually impaired. The back beams are already notched, providing tactile indicators for larger mass increments.

Weighing out a specific amount of a solid chemical involves setting the riders to the required amount in grams, and adding the chemical to the pan until the pointer rests at zero.

• Electronic top-loading balances with digital read-outs are also available and simple to use. The balance is turned on, the item to be weighed placed on the pan, and the mass in grams is displayed. Specific amounts of solid substances are obtained by adding that substance to the pan of the balance until the required amount registers on the display. Balances of this sort are available from science vendors such as CB, DE, and WNS.
• Spring scales are similar to produce scales at the grocery as shown in Figure 4.11. Objects are hung from a hook or placed in a pan that is connected to a spring with a scale indicating the mass of the object in grams. Pull spring scales are vertically oriented, and dial spring scales have a round face similar to a clock. Spring scales can also have a Newton scale parallel to the gram scale, which can be used to measure the force required to pull or move something against an opposing force. Dial face scales are the best to use for students with low vision, and are easily adapted for students who are blind. Braille labels can be affixed to the appropriate places on the face of a dial spring scale, allowing the student to feel and read where the needle rests for the measurement. SW offers a demonstration spring scale with large black numbers and a red indicator needle calibrated in grams for measuring mass only. CB offers both pull and dial spring scales in several gram and Newton ranges, appropriate for measuring mass and force, respectively.

Figure 4.11

Pull and Dial models of the spring scale. The scales are calibrated with grams for massing and weighing, and newtons for force determinations.

• Talking kitchen scales that measure and announce the mass of a substance or object in grams are available from MA, ILA, DL, and RNIB. Note that each vendor offers a different model with a different range of mass measurement.

Weighing Out Chemicals

• If a specific amount of a chemical is needed, the LHS balance, triple beam balance, and electronic digital balance are recommended for this purpose.
• Use a lightweight paper or cup to contain the substance being weighed out on the balance pan. Account for this extra weight during the process by adding the weight of the container to the amount of the substance required. Electronic digital balances usually have a "tare" feature, which zeros the balance with the empty container on the pan.
• Many utensils are available to scoop out solids from the source bottle or jar. Long-handled spoons are useful, but the bowl of the spoon is often too large. A sturdy, long straw can be used for this purpose. CB provides a variety of metal spatulas that have both spoon-shaped and flat ends.

VOLUME

The volume of anything, solid, liquid, or gas, is a measure of the amount of space it takes up. Regardless of the shape of an object, volume is often expressed as milliliters (ml) or cubic centimeters (cc, centimeters³). These units are equivalent, and the conversion of one to the other is always one to one. Volumes larger than 10 milliliters can be converted into other metric units such as centiliters (cl), deciliters (dl), and most commonly liters (l). Volumes less than a milliliter are usually converted into microliters (µl), or thousandths of a milliliter.

Determining the Volume of an Object

The volume of an object can be measured in several different ways depending upon its shape:

• For a regular geometric shape such as a cone, square, rectangle, or cylinder, the volume in cubic units can be calculated using the appropriate formula for that shape after determining the necessary linear dimensions such as length, width, height, diameter, etc.
• If the object is hollow with a thin wall, the volume can be determined by filling it with water, measuring the water in milliliters using a graduated cylinder, and converting these units into cc, if desired.
• If the object is oddly shaped but small enough to fit in a graduated cylinder, its volume is easily determined by measuring the amount of water it displaces as shown in Figure 4.12a. To do this, add water to the cylinder to a level that will cover the object and note the volume of the water at this point. Carefully place the object into the cylinder and note the new volume level. Calculate the difference in the two volume measurements and convert this amount from milliliters to cubic centimeters, if desired. If the object floats, use the same technique, but devise a way to keep the object immersed while taking the second volume measurement.

Figure 4.12a

Graduated cylinder method of determining the volume of an object.

Fill cylinder with a known amount of water that covers the object.
Place the object in the cylinder. Measure the level of the water again, and determine the change in water volume due to the displacement of the water by the object.

• The displacement method can still be used if the object is too large to fit in a graduated cylinder, as shown in Figure 4.12b. Find a container just large enough to hold the object. Place this container in a second container large enough to hold the first container and some overflow water. Fill the first container with water until it is just about to overflow. Carefully place the object into the first container and allow the water to overflow into the larger container. Measure the overflow water in the larger container in a graduated cylinder and convert the volume to cubic centimeters if desired. Alternatively, the overflow water can be massed, and that mass converted from grams of water to cubic centimeters.

Figure 4.12b

Overflow method of determining the volume of a large object.

1. Place small container inside large container and fill small container until it is brimming with water and about to overflow.

2. Place the object in the smaller container and allow the water it displaces to overflow.

3. Remove the smaller container and the object.

4. Pour the water that has overflowed into a graduated cylinder and measure the volume, or weigh it and determine the mass in grams. Recall that one gram of pure water converts to exactly one milliliter.

Measuring Liquid Volume

The accurate measurement of liquid volume is an important component of preparing solutions for experiments and demonstrations. For example, to prepare 100 milliliters of a 1 percent salt (NaCl) solution, exactly 100 milliliters of water is required to mix with one gram of salt. Graduated cylinders, ranging in size from several liters to 25 milliliters, with etched milliliter marks, are the standard liquid volume-measuring tools for more than 10 milliliters. Pipets are usually used to measure volumes less than 10 milliliters. More information on this lab ware is discussed below.

Safety Issues

Preparing solutions with liquids and solids can be messy and potentially dangerous. It is strongly recommended that students wear protective aprons and goggles when engaging in these activities (see chapter 2). As indicated in the chapter on safety, graduated cylinders, pipets, and other lab ware made of glass are not recommended. Most types of containers, such as beakers, graduated cylinders, Petri dishes, flasks, and test tubes are available from CB and WNS in different forms of plastic to avoid breakage. Pouring liquids from one container to another is most safely accomplished using a plastic funnel. LHS provides a very stable funnel stand that comes with a plastic funnel, and ordinary plastic funnels are available from CB and WNS.

The Meniscus

Liquids tend to rise or creep up the edges of glass graduated cylinders and pipets, forming a meniscus or concave top surface as shown in Figure 4.13a.

Figure 4.13a

A meniscus, or concave surface, develops when water and other similar fluids are poured into a glass graduated cylinder.

When a meniscus is present, read the liquid volume at its lowest point, and always at eye level. Liquids in plastic containers and cylinders do not form menisci, and the level of the liquid will be the same across the top as shown in Figure 4.13b. Making volume measurements in these types of containers is therefore easier.

Figure 4.13b

No meniscus is present when liquids like water are measured in a plastic graduated cylinder.

Liquid Level Indicators

Students who are visually impaired can use a liquid level indicator to prevent containers from overflowing. This device hangs on the rim of a container and will sound when the liquid reaches a particular level. The point at which it sounds varies with the model and cannot be adjusted, making it useful only for measuring approximate amounts. These devices are available from MA, ILA, and DL.

For use with non-toxic and non-corrosive materials, a simple line of jeweler's glue applied to the inside of a container at graduated volume lines will allow the student to place his index finger on the line and stop filling when the right level is reached.

Volume Measuring Methods

For all volume measurement techniques, it may be necessary to pour a small amount of the liquid of interest from the source jar or bottle into another container or beaker. This will make the use of the measurement device safer and easier.

Increasing Contrast

• A contrasting piece of paper can be placed behind a graduated cylinder so that the meniscus or liquid level can be more easily viewed.
• Food coloring added to the measured liquid will enhance the visibility of the liquid level, as long as addition of the dye does not interfere with the experimental procedure or react with the solution.
• Many graduated cylinders of different sizes are available in plastic, with tight-fitting square bases that increase the stability of the cylinder. These cylinders also feature a yellow stripe down their length, which contrasts well with the bold black numbers. All of these cylinders are available from CB.
• LHS offers the SAVI 50 milliliter plastic cylinder that comes with a float with an attached braille level indicator graduated in 5 milliliter increments. The float rises as fluid is added to the cylinder, increasing the visibility of the liquid level for the low vision student. The student without sight can read the braille on the indicator where it meets the top of the cylinder, which corresponds to the level of the liquid, as shown in Figure 4.14.

Figure 4.14

The SAVI 50 milliliter Graduated Cylinder with float and attached braille scale.
The cylinder is clear plastic with a square plastic base, longitudinal yellow contrast stripe, bold black lines and numbers, and a float with an attached braille scale.
As water is added to the cylinder, the float rises. The student who is blind can check the volume by pinching the scale at the level of the cylinder top; the braille number at that point indicates the level of fluid in the cylinder in 5 milliliter increments.

Modified Beakers

• Volumes may also be measured by the dipping method. Plastic beakers of the appropriate size modified with a hole at the desired volume level can be dipped into a larger vessel filled with water or other non-hazardous liquid, as shown in Figure 4.15a.
• The modified beaker can also be filled from the faucet or source bottle over a sink. The proper amount will be measured in the beaker when it is held level and fluid no longer drips or spills from the hole, as shown in Figure 4.15b.
• LHS sells the 100 and 1000 milliliter sizes of this type of modified beaker labeled with bold, large lettering for students with low vision, as shown in Figure 4.15c. Intact plastic beakers purchased from other vendors such as CB can be easily converted for any volume by cutting an appropriately placed hole.

Figure 4.15a, 4.15b, and 4.15c: SAVI Plastic Tripour Beakers

A plastic beaker with a hole drilled at the appropriate level will measure out exact amounts of liquid either by the dipping (a) or pouring method (b).

Syringes

• Plastic syringes can be used to deliver their total volume, or modified to deliver smaller amounts. Syringes are typically graduated in cubic centimeters (cc), which are identical in volume to milliliters (ml). CB offers syringes with total volumes of 1, 3, 10, 30, and 60 cubic centimeters.
• Notches cut at intervals along the plunger of all syringes except the one cubic centimeter size can provide a tactile indication of specific volumes, see Figure 4.16a.
• All syringes except the one cubic centimeter size can be modified with a pop rivet, push pin, or thumb tack placed at a particular point on the syringe barrel, providing a stopping mechanism for the plunger in order to deliver specific volumes, as shown in Figures 4.16a and 4.16b.

Figure 4.16a and 4.16b

Syringes modified with notches, rivets, push pins, thumb tacks; pop rivet gun, pop rivets

• Notches can be cut into the plunger of the syringe, providing a tactile indication for particular volumes.
• Rivets or other devices placed at particular points in the barrel of the syringe act as stops allowing only certain amounts of fluid to be taken up and subsequently delivered.
• Pop rivets and guns are available at hardware stores. 1/8 inch grip range rivets are small enough for syringes ranging in volume from 5 cubic centimeters to 60 cubic centimeters.
• One cubic centimeter syringes can be modified to deliver fractions of a milliliter by forming a hole at the top of the plunger and the barrel, and creating a stopping mechanism with sturdy string or a straightened and trimmed paperclip, as shown in Figure 4.16c. Holes are easily made with an exacto knife fitted with a number 11 blade.
• LHS offers a large syringe modified to deliver 25 cubic centimeters with a notch in the plunger and 50 cubic centimeters with a pop rivet installed in the barrel.

Figure 4.16c

One cubic centimeter syringes modified with string or straightened paper clip as stopping devices

Bottle Top Dispenser

A bottle top dispenser is a container fitted with a device that will deliver a constant measured volume multiple times. These containers can be refilled as needed, and the volume dispensed may be fixed or adjustable. Adjustable models are more expensive and must be set by a sighted person. All model types are available from CB; see Figure 4.17.

Figure 4.17

Bottle Top Dispenser
After the scale is set to the volume desired, the bottle top is depressed and the set volume is dispensed out of the spigot. The reservoir can be refilled as often as necessary.

Talking Measuring Jug

ILA offers a Talking Measuring Jug, which announces the volume of fluids or solids poured into the container.

Pipets and Pipettors

Small volumes of liquid (1-10 milliliters and fractions of a milliliter) are usually measured with pipets, which come in a variety of forms:

• Glass or plastic tube-like pipets with milliliter or microliter gradations are filled and dispensed with a pipet filler or pipet aid, both available from CB. Pipet fillers and aids are devices that form suction to draw the fluid up the pipet to the appropriate volume marking.
• Forming suction by mouth is unsafe and therefore not recommended.
• The contrast of the markings on the pipets can be enhanced by slipping the pipet through a yellow or pink index card or piece of paper cut with two horizontal slits, so that the pipet is in front of the part between the slits, as shown in Figure 4.18.

Figure 4.18.

Increasing contrast with a colored background.
The pipet is slipped into a yellow or pink index card with two slits so that the card creates a background for the pipet scale and the liquid level or meniscus is clearly observed.

• Pipettors are devices that dispense a preset variable or constant volume of liquid via an attachable and disposable plastic tip, usually in microliter (µl) amounts. Adjustable models work with a dial mechanism and require the assistance of a sighted person. The pipet trigger is released and depressed in order to take up and dispense the liquid, respectively. Be sure to purchase plastic tips that are appropriate for the specific pipettor; see Figure 4.19.

Figure 4.19

Adjustable and Fixed Volume Pipettors
Fixed volume pipettors deliver the same volume every time. Other pipettors have a dial mechanism that can be adjusted to the desired volume within particular ranges. Both styles require the use of disposable plastic tips that contain the liquid. These types of pipettors are available from CB, SK, SW, and WNS.

Measuring Liquid Volume with a Balance

Because the volume of pure water, or water with nothing dissolved in it, is directly related to its mass, exact volumes can be weighed with a balance. Conversion of grams to milliliters is simple because one gram of pure water is exactly 1 milliliter, and this one-to-one relationship can be extended to any volume. Note that dissolving anything in water, such as sugars or salts, will increase the mass of the liquid per unit volume, or in other words, its density (mass per unit volume). In these cases, the density of the liquid must be known in order to "weigh out" the exact volume desired. For example, if the density of 0.5 Molar NaOH is 1.20 grams/milliliter, and 10 milliliters is required, 12.0 g would need to be weighed out on the balance.

Stirring Liquids

Magnetic Stirrers and Stirring Bars

Solids may be dissolved in water or other liquids by adding the measured amount to the fluid as it's being stirred. This is most easily done using a magnetic stirrer and a teflon coated magnetic stir bar. The liquid is poured into a beaker or other receptacle of the proper size, a teflon coated stir bar is carefully added, and the stirrer is turned on. The added solid will dissolve very quickly as the magnet in the stirrer rotates, as shown in Figure 4.20. Note that magnetic stir bars are heavy and dropping them carelessly into a glass receptacle can cause breakage. Magnetic stirrers and stirring bars can be purchased from most science vendors, such as CB, WNS, ES, and SW.

Figure 4.20

A teflon-coated stirring bar is added to the liquid and solid to be mixed, and placed on the magnetic stirrer. The stirrer is turned on and the magnet begins to turn, dissolving the solid.

Stirring Rods

Plastic utensils such as cocktail or coffee stirrers can be used to stir and dissolve salts and other substances in fluids. WNS also offers a 9.5 inch polypropylene stirring rod.

TIME

The SI unit for time is the second (s), but it is still acceptable to use minutes (min) and hours (h) in some derived units such as kilometers per hour and grams per minute.

The official United States time is kept by an atomic clock located in Fort Collins, Colorado, and can be accessed at the following internet link: http://www.time.gov. Atomic clocks use the very consistent and reliable resonance frequency of the cesium atom as the standard on which to measure a second. This technology has replaced the quartz clock, the accuracy of which can be adversely affected by changes in temperature. A large display radio controlled atomic clock is available from DL.

Long time intervals, such as minutes and hours, are measured easily with a large analog or digital clock, but keeping track of seconds requires a stopwatch or timer for greater accuracy. Kitchen digital and analog timers with large numerals, as well as braille and talking timers, are available from ILA, LS & S, DL, and MA.

TEMPERATURE

Some experimental procedures require the measurement of the air, water, or solution temperature, or a water bath in order to raise or lower the temperature of another substance that cannot be heated or cooled directly.

Measuring Temperature

Scientists measure temperature with thermometers calibrated with the Celsius scale, which is based on the freezing point
(0 degrees C) and boiling point of pure water (100 degrees C). Note that the Fahrenheit scale is inappropriate for scientific measurement.

To convert Fahrenheit to Celsius degrees, use the following formula: C = 5/9 (F -32). To convert Celsius to Fahrenheit degrees use this formula: F = (9/5 C) + 32.

Conventional Thermometers

Unprotected glass thermometers filled with mercury or red alcohol are commonly used in the laboratory, but are not recommended due to the high probability of breakage. If this type of thermometer must be used, insert it into a rubber or cork stopper with a central hole. The thermometer can then be held in the receptacle with a clamp attached to the stopper and a support stand. Make sure that the bulb of the thermometer does not touch the bottom or sides of the receptacle, as shown in Figure 4.21.

Figure 4.21

Proper Measurement of Temperature with a Conventional Glass Thermometer
The thermometer is put through a rubber or cork stopper and attached to a support stand with a utility clamp. The thermometer is placed so that the bulb is near the bottom of the container, but not touching either the bottom or sides of the container.

• Glass alcohol immersion thermometers protected by an aluminum frame are available from CB. These thermometers can be immersed in a fluid to measure temperature without the bulb touching the bottom of the beaker or container, and have easy-to-read large numbers and markings.
• Other thermometers are available that have immersible and unbreakable glass-free probes. For example, ES and CB offer large numeral digital electronic indoor/outdoor thermometers that measure a wide range of temperatures in Celsius degrees.
• An unbreakable steel probe thermometer with a Celsius digital read-out is available from CB.
• Talking indoor/outdoor digital thermometers are available from LS & S, MA, and DL, also with Celsius scale and an unbreakable probe.
• LHS offers the SAVI/SELPH braille/large print, glass-free thermometer; see Figure 4.22.

Figure 4.22

SAVI/SELPH Thermometer
This thermometer has a dial gauge with black print and braille numbers, and a metal tactile pointer connected to a metal coil underneath. The entire coil must be immersed in liquid for at least 10 seconds for the correct temperature to register, and it must be read while still in the liquid. Changing air temperatures can be accurately detected within 10 minutes. Note that this thermometer will melt at very high temperatures.

Cooling

An ice bath will chill fluids and objects down to approximately 0 - 3 degrees C, if necessary. The amount of time this takes will depend on the system involved, and will require the addition of more ice if the whole system is kept at room temperature. A refrigerator and freezer, if available, are also useful for chilling substances or objects.

Heating

Raising the temperature of water or a solution requires the addition of heat, which can be accomplished in several different ways. It is important to remember that all equipment and accessories associated with this process will become very hot; care must be taken to allow them to cool before further manipulation. The use of heatproof autoclave or Kevlar® gloves available from CB is highly recommended.

Bunsen Burner

Many laboratories are equipped with natural gas lines and Bunsen burners, which produce an adjustable flame and require instruction for safe operation. Only fire/heat proof borosilicate glass containers, such as Pyrex^® available from CB and other vendors, should be used to hold substances to be heated.

Instructions for the safe operation of a Bunsen burner are as follows; see Figure 4.23:

• The instructor should have the gas main turned off until all Bunsen burners are connected properly with tubing to the gas outlets. All gas outlet valves at student stations should be in the off position (perpendicular, or at 90 degrees to the gas outlet).
• Connect the gas outlet to the Bunsen burner gas inlet with intact rubber tubing. Turn the gas flow control (knurled screw) located underneath the vertical burner barrel counter-clockwise to the off position; make sure it is loosely screwed into the base. Rotate the air vent barrel so that the vents are fully covered. The instructor can now turn on the gas main.
• Turn on the gas outlets at each student station by turning the valve so that it is in line with the tubing leading to the Bunsen burner. Gas is never regulated with this valve; the valve should be in either the fully "on" or fully "off" position.
• The Burner is ready to be lit with long tapers, a flint-type gas lighter, or a piezo electric gas lighter. Strike the taper, flint, or lighter over the vertical burner barrel and turn the gas flow control screw clockwise for two turns to the "on" position (unscrew it partially).

Note: The use of regular short wooden or paper matches for lighting a Bunsen burner is not recommended.

• A yellow, luminous flame should appear; adjust its height to 7.5 centimeters by turning the gas flow control (clockwise for a larger flame and counter-clockwise for a smaller flame). This flame is relatively cool because air is mixed with the gas at the point where it is being burned.
• Rotating the air vent barrel to slowly open the air vents can produce a hotter non-luminous blue flame, most desirable for heating fluids in glass beakers or flasks. Air is now mixing with the gas before it is ignited, and a rushing sound can be heard. Adjust the vents so that the flame is dark blue, 3 to 6 centimeters high and burning quietly.
• When the heating process is over, turn the gas off at the outlet valve so that it is perpendicular to the tubing leading to the Bunsen burner. Turn the gas flow control screw to the "off" position (counter-clockwise) and close the air vents with the air vent barrel.

Figure 4.23

The Bunsen Burner
The diagram shows the different parts of the Bunsen burner: burner barrel, air vent barrel, gas flow control, base, gas inlet, and rubber tubing.

Precautions

• Students who are visually impaired can safely operate a Bunsen burner, but practice and instructor supervision are highly recommended. Complete visual and tactile familiarization with all parts of the system is necessary before actual use is attempted, and the instructions should be followed explicitly.
• It is not recommended that students use matches to light the Bunsen burner. Flint or piezo electric gas lighters produce sparks rather than a flame, and are safer options. Flint lighters can be purchased from CB, and piezo electric gas lighters can be purchased at discount stores.
• Sound is another cue that can be used by students, particularly when determining if the flame has gone out unexpectedly. This can happen if the airflow is too high. All students should learn to listen for the difference between a lit and unlit burner with the gas turned on.
• Even a hot dark blue flame can be difficult to see by those without visual impairments. The visibility of the flame can be enhanced by placing a piece of wire gauze above it, supported by a tripod or support ring clamped to a stand; the gauze will glow when heated; see Figure 4.24.

Figure 4.24

Bunsen Burner with Wire Gauze Above Flame to Increase Visibility
A support ring is clamped to a stand and supports a piece of wire gauze above the flame of the Bunsen burner. The gauze will glow when hot.

Hot Plate

The hot plate is a safer option for heating liquids. The container is placed on top of the hot plate, which is turned on to the appropriate heating level. The hot plate as well as the container will become very hot. Care must be taken to prevent burns and the use of Kevlar^® heat resistant gloves available from CB is highly recommended. Hot plates can be purchased from CB and other science product vendors.

pH

The acidity or alkalinity of a solution or substance is determined by the relative concentration of hydrogen ions (H⁺) in it. This is measured by taking the solution's pH, which stands for potential hydrogen. The pH scale consists of numbers ranging from 0 to 14, which are equal to the negative base 10 logarithm of the hydrogen ion (H⁺) concentration of the solution. More simply, this means that as the pH increases, the hydrogen ion concentration decreases tenfold for each single digit increment, and vice versa. For example, an increase in pH from 7 to 8 represents a tenfold decrease in hydrogen ion concentration; i.e., the solution is 10 times less acidic. Conversely, a decrease in pH from 8 to 7 represents a ten-fold increase in hydrogen ion concentration; that is, the solution is 10 times more acidic. Pure water is a neutral substance, which means that it is neither acidic nor basic, and it has a pH of 7. Acidic solutions, such as lemon juice, contain a relatively high concentration of hydrogen ions and have a lower pH than pure water (0 - 6). Conversely, alkaline or basic solutions (such as ammonia) contain a relatively low concentration of hydrogen ions and have a higher pH than pure water (8 - 14).

As pH rises, a solution becomes more alkaline or basic; as pH falls, a solution becomes more acidic. The pH of a solution can be measured with a hydrogen ion sensitive probe attached to a meter, or colorimetrically with pH sensitive paper.

Measuring pH

ph Meter

The pH meter is an electronic device consisting of a digital or analog meter connected to a probe equipped with a special membrane sensitive to hydrogen ions (H⁺). When the meter is properly calibrated and the connected probe dipped into a solution of a particular pH, the concentration of hydrogen ions will cause the meter to register at the appropriate measurement. Although the pH probe has a protective outer plastic sheath, the inner H⁺ sensor is usually made out of glass, making it still quite delicate and breakable. Combined with the meter, these devices are available from CB and typically are quite expensive; see Figure 4.25a and 4.25b.

Figure 4.25a

Benchtop pH Meter
A glass probe sensitive to changes in pH is connected to the digital read-out meter.

Figure 4.25b

Portable pH Meter with Digital Readout
The pH sensitive probe and digital read-out meter comprise this hand-held device.

Colorimetric Methods

If meters are inappropriate or unavailable, other methods exist to measure or estimate pH. Many naturally occurring pigments or dyes are sensitive to pH and will change color when they are exposed to either an acid or base. This property can be used to determine the pH of a solution into which paper impregnated with this type of pigment or dye is dipped.

Litmus Paper

For simple determinations of whether a solution is acidic or basic, red or blue litmus paper can be used. The pigment in this paper is red in the presence of acid and blue in the presence of base. Red litmus paper, which is actually pink, will remain red in the presence of an acid or turn blue in the presence of a base. Conversely, blue litmus paper will remain blue in the presence of base but turn red in the presence of an acid. These strips are for single use only. The student with low vision can use a magnifier to enlarge the paper strip and determine if a color change has occurred. Talking color detectors are available from several vendors and can be used by students who are blind or colorblind in order to determine the results of these colorimetric tests (MA, AM, Color Test from APH, ILA).

pH Indicator Strips

For more exact pH measurements without the use of a meter, pH test strips are recommended and available from CB. Many varieties are available, but the basic principle is the same. Paper strips impregnated with pH sensitive pigment is dipped into the solution. The color change is matched to the color scale on the dispenser in order to determine the pH. Test strips that indicate the full pH range from 0 to 14 or narrower ranges are available. As with litmus paper, pH test strips are for single use only. The student with low vision could benefit from using a magnifier as the test strips are usually small in size and the color changes can be subtle. The student with blindness can use the talking color detector (see section on litmus paper) to assess a color change and enlist the help of a sighted partner to determine the exact pH.

Other suggestions for adapting science procedures for students who are visually impaired:

• To demonstrate chemical reactions, choose those that result in dramatic color changes or that can be detected by other senses:
  • Mixing vinegar and baking soda causes bubbling or fizzing that can be heard; amplify this if necessary
  • Drops of iodine solution will turn white cornstarch black
  • Heat packs demonstrate exothermic reactions
  • Cold packs demonstrate endothermic reactions
  • Dissolve Potassium Chloride (KCl) or Ammonium Chloride (NH₄Cl) in water (solution becomes cold)
  • Dissolve plaster of Paris with water (mixture turns warm and hardens)
  • Dissolve Calcium Chloride (CaCl₂) in water (solution becomes warm)
  • Use perfume to demonstrate diffusion in air, rather than a drop of dye or ink in water
• Substitute a buzzer instead of a light to demonstrate a complete electrical circuit
• Use Wikki Stix^® to make quick tactile models
• Consult APH Guidelines for making tactile graphics: www.aph.org/edresearch/guides.htm
• Prepare tactile diagrams with microcapsule paper and an image enhancement device:
  • Draw a diagram with a china marker or copy a diagram from a master on a copy machine onto microcapsule paper
  • The prepared microcapsule paper is then put through one of the following image enhancement devices to make the tactile image by heating the paper and swelling the dark lines: TIE (Tactile Image Enhancer), PIAF (Pictures in a Flash), or Swell-Form machine (see contact information for these devices below).
  • Humanware Pulse Data
    
    175 Mason Circle
    Concord, California 94520
    800-722-3393
    www.humanware.com
    
    This company sells a tactile graphic making device called Pictures in A Flash (PIAF) and microcapsule paper.
  • American Thermoform Corporation
    1758 Brackett Street
    La Verne, California 91750
    800-331-3676
    www.americanthermoform.com
    
    This company sells the Swell-Form machine and Swell-Touch paper (microcapsule paper) for making tactile graphics.
  • Repro-Tronics, Inc.
    75 Carver Avenue
    Westwood, New Jersey 07675
    800-948-8453
    www.repro-tronics.com
    
    
    This company offers the Tactile Image Enhancer (TIE) and Flexi-Paper (microcapsule paper) for making tactile graphics

Table 4.2
Table of Imperial* and Metric Equivalents

Imperial unit	Imperial equivalents	Metric equivalents
Length	Length	Length
1 inch (in)	~	2.5 centimeters (cm)
1 foot (ft)	12 inches	0.3 meter (m)
1 yard (yd)	36 inches	0.9 meter
1 mile (mi)	1760 yards	1.6 kilometers (km)
Volume	Volume	Volume
1 cubic inch	~	16.4 cubic centimeters (cm3)
1 cubic foot	1728 cubic inches	0.03 cubic meter (m3)
1 fluid ounce (fl oz)	~	29.5 milliliters (ml)
1/4 cup (c)	2 fl oz	59 ml
1/2 cup	4 fl oz	118 ml
1 cup	8 fl oz	236 ml
1 pint (pt)	16 fl oz or 2 c	472 ml or 0.47 liter (l)
1 quart (qt)	32 fl oz or 4 c	944 ml or 0.94 liter
1 gallon (gal)	128 oz, 16 c, 8 pt, 4 qt	3.8 liters
1 teaspoon (t)	~	5 ml
1 tablespoon (T)	3 teaspoons	15 ml
Weight/Mass	Weight/Mass	Weight/Mass
1 ounce (oz)	~	28.4 grams (g)
1 pound (lb)	16 oz	454 g or 0.45 kilogram (kg)

*Imperial refers to United States Standard Imperial quantities for volume.

The Following Imperial-Metric conversion web sites make these conversions very simple:

http://encarta.msn.com/media_701500646/Imperial_and_Metric_Conversion_Factors.html
http://www.onlineconversion.com/
http://www.sciencemadesimple.net/conversions.html

Chapter 5

Models and Teaching the Visually Impaired

"You probably only understand something to the degree that you can make a physical, visual model of it."
Philip Morrison

"You only understand something to the degree that you can make an analogy about it. Analogies use physical images represented by words; they are the "hands-on" of language."
Kerry Ruef

"... the whole of science is shot through and through with metaphors, which transfer and link one part of our experience to another, and find likenesses between the parts."
Jacob Bronowski

What Is a Model?

Models are used all the time. Usually, a model is a tangible, three-dimensional representation of something that cannot be perceived directly by touch, hearing, or sight. Examples of these kinds of abstract concepts are the solar system or a single atom.

Models can be constructed so they are visually, but not functionally, accurate and vise versa. For example, a scale model of the solar system could be made with different color and sized balls placed in static positions in the proper order with wire. This model is not accurate with respect to the planets' chemical composition or their phases. It also doesn't demonstrate their respective revolutions around the sun, but it does give a good idea of what the solar system really looks like.

On the other hand, a model does not have to look like the object that it represents. For example, a model of the solar system in which students play the parts of the sun and planets as they move in their respective orbits is a functional model rather than one that is visually accurate. The movement of the students in circular patterns around the "sun" is analogous to the planetary orbits, just as the movement of student "electrons" around a student "atomic nucleus" is analogous to a current model of atomic structure.

Both kinds of models, scale and functional, are concrete rather than imaginary or metaphoric, which means that they can be touched or perceived tactually. Photographs and illustrations also can be concrete models even though they are two-dimensional representations of concepts or objects.

It isn't difficult to see how important models are as a teaching strategy for all students, especially those who are visually impaired. This is particularly true for teaching a subject like science, which is filled with abstract concepts. To meet this need, textbooks have become more and more visual in recent years, adding lots of graphic images.

Teachers should not limit themselves or their students to one particular model of a concept, or to just concrete models. A model can be a comparison or something that exists only in the mind, such as a simile or metaphor. An example of this could be "the waterfall flowed like a faucet." A model also could be a hypothetical prediction, such as "if global warming is not curbed, the polar ice caps will melt." These and other models can help make an abstract concept more concrete.

Abstract models such as diagrams, tables, and graphs are useful too; but these types of models are symbolic and generally require interpretation, as well as an understanding of the system they represent. Graphs show the relationship between two or more conditions or variables of a system, and need to be related to the real objects they represent for them to have meaning.

The important thing to remember when using models is to understand their limitations. Usually one type of model will illustrate only one or two features of a concept. A more complete understanding is gained when several kinds of models are used for the same concept.

While it is best to use real objects to explain a concept, this is not always possible or practical. Note also that it is not appropriate to use miniaturization to represent full scale objects to students who are visually impaired.

Examples of Models in Four Major Fields of Science

Biology

The smallest unit of all living organisms is the cell. The concept of the cell can be demonstrated in many different ways:

• Making a simple line (bold or raised-line for the visually impaired student) drawing of a cell with its organelles (nucleus, vacuole, cell membrane, mitochondria, etc.) clearly labeled; see APH guidelines for making tactile graphics; www.aph.org/edresearch/guides.htm
• Students can form a table on the blackboard or overhead projector listing cellular organelles in the first column and their functions in a second column.
• A three-dimensional model can be formed with a Ziploc^® plastic bag filled with gelatin for the cytoplasm and odds and ends representing the organelles.
• The semi-permeable nature of the cell membrane can be demonstrated with a plastic baggie filled with water and a few grams of starch. If the baggie is placed in water containing a few drops of iodine, the starch in the baggie will turn black within a half-hour. This shows that iodine, which is a small molecule, moves into the baggie, combines with the starch, and turns it black. Since the water outside the baggie does not turn black, this demonstration shows that starch does not move or diffuse out of the baggie. This is because starch is a very large molecule and cannot move through the tiny pores in the baggie.
• A tactual demonstration of the semi-permeable nature of the cell membrane can be shown with a colander. A mixture of sand and beans poured into the colander results in the complete passage of the sand, but retention of the beans. The holes in the colander and baggie represent the "holes" or pores in the cell membrane, which only allow the passage of molecules that are small enough.

Note how each of these models is incomplete in some way, yet they describe discrete aspects of the unit cell concept. All the models taken together provide for a more complete understanding of the structure, function, and visualization of an individual cell.

Chemistry

The smallest particle of any pure substance or element is the atom. A simple diagram of a hydrogen atom could be drawn with a circular nucleus, representing one proton, with a single orbiting electron. This and other models become more complex when molecules, or atoms bonded to each other, are depicted. In this case, not only the individual atoms, but also their relationship to each other must be represented. For example, hydrogen gas exists as two hydrogen atoms bonded together. This bond, consisting of one pair of shared electrons, can be represented in many different ways:

• The chemical formula, H₂, indicates that two hydrogen atoms, represented by letters, are bonded together.
• Electron dot notation (H:H) and bond-line formula (H-H) both indicate that a pair of electrons is shared, but both still use letters to represent the atoms.
• Ball and stick models represent the associated atoms as spheres and the bonding electrons as sticks. These models can be drawn as a diagram or actually constructed with various materials.
• CB offers many molecular model kits, including a giant-size chemistry set, which provide excellent visualizations of the concept of the molecule for all students.

Earth Science

The concept of continental drift is often used to explain the current location of the continents. Physical features of the earth supporting this hypothesis can be demonstrated in several ways.

• A color contrasting or raised relief classroom globe can be used to visually determine the outlines of each of the continents. Thin sheets of tracing paper can be laid on each continent, and their outlines traced and cut with scissors. The cut-outs can be fitted together to form a likeness of the single landmass, Pangea, that is believed to have given rise to the current seven continents 300 million years ago.
• This kind of exercise also can be done with lightweight modeling clay, such as Crayola^® Model Magic^®, which comes in several different bright colors and is available in most discount stores. The clay can be spread from the center of the continent toward the edges and then removed and allowed to dry. These models of the continents then can be fitted together to resemble Pangea.
• To reinforce and simulate the concept of continental break-up, allow a thin layer of mud (0.5 liter dirt plus 1 liter water) to dry in a cookie sheet. Pressing on the edges of the dried mud cake will cause it to crack into irregular shapes. If the pieces are carefully removed, they can be replaced in their original positions.
• Convection currents form within the Earth's liquid mantle and provide the driving force behind continental drift. As the mantle is heated from deep within the Earth, it slowly rises and erupts between crustal plates on the surface. This accounts for the movement and separation of the continents. Convection currents can be demonstrated with two strips of paper slowly fed upwards through a slit in the bottom of an open shoebox held up side down. The movement of pieces of clay on the edges of the strips shows the displacement of older areas of Earth's crust as shown in Figure 5.1.

Figure 5.1

"Reprinted by permission of John Wiley & Sons, Inc. from Earth Science for Every Kid. Janice Van Cleave, copyright © 1991"

Physics

Although the concept of energy is most often associated with Physics, it is fundamental to all fields of science. Defined as the ability to do work, or move something against an opposing force, energy is an abstract and difficult concept to convey to all students. Energy can take several different inter-convertible forms such as heat, light, sound, chemical, electrical, and mechanical. Energy can change forms but can never be lost or created.

Energy can also be in one of two states. Potential energy refers to energy that is stored and not currently being used. The fuel in a car's gas tank has stored or potential energy within the bonds of the molecules making up the fuel. Kinetic energy, on the other hand, is the energy of motion. When the fuel is burned after the ignition is turned on, the stored chemical energy is converted into kinetic or mechanical energy, which moves the car.

Although it can change form and state, the conversion of energy is never 100 percent efficient. This means that the amount of energy that actually performs work during a conversion is always less than what was available from the beginning. When work is performed during an energy conversion, the residual energy is usually released as heat. For example, the chemical energy in the gasoline that fuels a car is partially converted into mechanical energy which causes the car to move. The remaining chemical energy of the original gasoline is converted into heat and sound in the engine; note that these latter forms of energy do not perform work or move the car in this system.

Energy changes can be demonstrated in many different ways:

• A stretched rubber band will feel warmer to the touch than a relaxed rubber band when placed against the forehead or lips. Mechanical energy stored in the rubber band is released as heat when it is stretched.
• The energy stored in a ball situated on the high end of a ramp is released when the ball rolls down. If the ball hits a cup in its path at the bottom of the ramp, the released mechanical energy will perform work, or move the cup a specific distance. More work can be done on the cup if the ramp is elevated higher; that is, the cup will move farther. A similar demonstration of the same concept that is both visual and auditory is the Milton Bradley^® game of Mouse Trap^® in which a ball follows a complicated path eventually releasing a trap over the mouse. Even though it's not detectable in the game or the ramp and cup situation, heat is also released whenever the ball moves.
• The stored mechanical energy in an inflated balloon is released when it is popped with a pin or the knot untied. The released energy causes the deflating balloon to move crazily and also causes the sound associated with sudden popping or the slower loss of air when the knot is untied.
• There are some situations in which heat can be harnessed to perform work. A simple demonstration of this is as follows: place a glass pop bottle in the freezer for about a half an hour. While the bottle is chilling, cut a cardboard circle that will fit snugly into the opening of the bottle and saturate it with water. Remove the bottle from the freezer and place the wet cardboard circle in the opening. Rub the palms of the hands together about 20 times and place them around the sides of the bottle. The heat will warm the air in the bottle and cause it to expand and pop the cardboard top off. This is an example of the transformation of heat energy to mechanical energy, as in a steam engine.

Suggested Modeling Materials

There are many materials on the market from which models can be constructed, in addition to the ones mentioned above.

Model Magic^®
Homemade modeling compound
Modeling Clay
Silly Putty^®
Casting plaster
Wikki Stix^®

CB offers a large assortment of scale, functional, and preserved life models suitable for visual and tactile exploration of all things scientific including concepts and organisms. A non-comprehensive list follows:

Skulls & skeletons
Flowering plant organs
Cells & cell division
Animal & plant development
Plate tectonics
Invertebrate animals
Unicellular plants & animals
Vertebrate animals
Vertebrate organs
Vertebrate organ systems
Globes & maps
Landforms & topograpy

APH offers the following science products that facilitate the preparation or presentation of models:

Sense of Science: Plants
Sense of Science: Animals
Tactile Demonstration Thermometer
Basic Science Tactile Graphics
U.S. Puzzle Map
Basic Tactile Anatomy Atlas
Tactile and Visual Globe
Tactile Graphics Starter Kit
Braille World Atlas
Picture Atlas of our Fifty States
Map Study I: Maps Represent Real Places
Map Study II: Basic Map Reading Concepts
Recognizing Landforms: An Audio-Tutorial Program in Map Study

Also see APH's Guidelines for Design of Tactile Graphics: www.aph.org/edresearch/guides.htm

TAEVIS (Tactile Access to Education for Visually Impaired Students) at Purdue University offers a Tactile Diagram CD with approximately 4500 high-quality diagrams. The diagrams can be printed onto microcapsule paper for the production of tactile images with a TIE (Tactile Image Enhancer), PIAF (Pictures in a Flash), or Swell-Form machine (see contact information for these devices below). Subjects include Biochemistry, Biology, Chemistry, Math, Graphs and Shapes, and others.

TAEVIS
Purdue University
Young Hall, Room 850
302 Wood Street
West Lafayette, IN 47907
765-496-2856
www.taevsionline.purdue.edu/TAEVIS_Diagram_CD.html

Humanware Pulse Data
175 Mason Circle
Concord, California 94520
800-722-3393
www.humanware.com
This company sells a tactile graphic making device called Pictures in A Flash (PIAF) and microcapsule paper.

American Thermoform Corporation
1758 Brackett Street
La Verne, California 91750
800-331-3676
www.americanthermoform.com
This company sells the Swell-Form machine and Swell-Touch paper (microcapsule paper) for making tactile graphics.

Repro-Tronics, Inc.
75 Carver Avenue
Westwood, New Jersey 07675
800-948-8453
www.repro-tronics.com
This company offers the Tactile Image Enhancer (TIE) and Flexi-Paper (microcapsule paper) for making tactile graphics Models and Teaching the Visually Impaired.

Chapter 6

Data Collection, Presentation, and Reporting

"When found, make note of it."
Charles Dickens

"I wanted to know every strange stone, flower, insect, bird, or beast."
George Washington Carver

Data Collection

A data collection sheet is part of a good experimental plan and can be prepared on a notepad or secured on a clipboard. It's appropriate to use either lined paper or graph paper for data collection, both of which are available from APH in versions specially prepared for the visually impaired. APH offers bold-lined paper in pads, notebooks, and loose sheets, and graph paper in various square and grid sizes in bold-line and embossed versions.

Organize data from the start by labeling columns and rows for the dependent and independent variables. Recall that the independent variable is the manipulated and therefore known factor in the experiment; it is "the cause." The independent variable may include time, and any controlled condition of the experiment. The dependent variable is the feature in question, or the unknown that is being measured; this could be called "the effect."

A data table helps in the presentation of results in the form of a graphic. Graphics visually illustrate the relationship between cause and effect, and facilitate data interpretation.

The best graphic to choose will depend upon the variables of the experiment and the data they generate. Quantitative data are those that are numerical and generally in units. When all variables are quantitative, it's best to transform the data into a point-and-line graph or a frequency histogram. When at least one variable is qualitative or descriptive, the data are best represented as a bar graph or circle or pie graph.

Making Tables and Graphs with Data from Observations or Experiments

This section is followed by specific resources for preparing tactile graphic diagrams for students who are visually impaired.

Frequency Diagram or Histogram

Sunflower hulls are usually white with black stripes, but the number of stripes is variable from seed to seed. A way to visualize this variation is to construct a frequency diagram or a histogram. This type of diagram gives a picture of the distribution of the variations in one particular feature or characteristic in a population of individuals.

Table 6.1 shows the number of stripes on 30 different sunflower seed hulls.

Table 6.1

Number of Stripes on 30 Different Sunflower Seed Hulls

# stripes	# stripes	# stripes	# stripes	# stripes
3	4	8	4	7
9	7	8	8	8
8	9	3	5	10
9	4	8	9	11
5	8	7	6	8
9	10	11	10	12

These data can be transformed into a frequency distribution as shown in Table 6.2, which indicates the number or frequency of seeds, in each stripe number category.

Table 6.2

Frequency Distribution; Number of Seeds in Stripe Number Categories

Number of stripes	Number of seeds
1	0
2	0
3	2
4	3
5	2
6	1
7	3
8	8
9	5
10	3
11	2
12	1
13	0

Now a histogram can be constructed by making a graph with two axes. The vertical or y-axis shows the number of individuals or the frequency, and the horizontal or x-axis shows the variations in the feature of interest, or number of stripes per hull in this case (categories). The histogram will indicate patterns at a glance, as shown in Figure 6.1.

Figure 6.1 Histogram

Sunflower Hull Stripe Number
A bar graph is shown with two axes. The x-axis is divided into units from 1 to 13, denoting the number of stripes commonly found on sunflower seed hulls. The y-axis indicates frequency, or the number of seeds with a particular number of stripes. In this graph, there are 0 seeds with 1 and 2 stripes. Bars on the histogram indicate that there are 2 seeds with 3 stripes, 3 seeds with 4 stripes, 2 seeds with 5 stripes, 1 seed with 6 stripes, 3 seeds with 7 stripes, 8 seeds with 8 stripes, 5 seeds with 9 stripes, 3 seeds with10 stripes, 2 seeds with 11 stripes, 1 seed with 12 stripes, and 0 seeds with 13 stripes.

Histograms can be prepared with bold-line and embossed graph paper, available from APH, and LHS offers a plastic histogram board with tactile markers to set off 10 columns. Any kind of removable adhesive-backed stickers can be used to indicate numbers of individuals within the range of the observed feature. Foam adhesive-backed circles are available from LHS. Histograms can also be constructed with a non-aluminum metal cookie sheet and magnets placed in appropriate columns, or with cardboard, string, and thumbtacks. Microsoft© Excel offers many graphing options, including histograms that can be made from appropriate data sets.

Point and Line Graph

If all of the observed variables in an experiment are quantitative, particularly if one of those variables is time, a point and line graph is an appropriate way to present the data. For example, seedling stem growth can be monitored over a period of time under several different conditions. This experiment has two independent or cause variables; one is time, and the other is the growth condition. The dependent variable, or effect, is the seedling stem height. The treatments are normal growth conditions or the control, and then some variation in the growth conditions such as the amount of light, water, or nutrients, which would be the experimental or test treatments. Organize the data as shown in Table 6.3.

Table 6.3

Height of Sunflower Seedlings in Response to Different Light Levels

Time (days)	Height, cm low light (treatment 1)	Height, cm medium light (control)	Height, cm high light (treatment 2)
2	2	6	8
4	5	9	15
6	6	12	20

Plot the results on a graph with the scale for the independent variable, time, on the x-axis and the scale for the dependent variable, stem height, on the y-axis. Regular, bold-line, or embossed graph paper is appropriate for this type of graph. At each time increment, a corresponding data point is plotted for each experimental condition until the experiment is over. The points, which are represented by a different symbol for each experimental condition, are connected with a line in order to illustrate any patterns. This data set would produce three sets of points, connected by lines as shown in Figure 6.2.

Figure 6.2 Point and Line Graph

Effect of Light Levels on Sunflower Seedling Height
The x-axis, denoting time, is divided into increments of 2, 4, and 6 days. The y-axis, denoting seedling height, is divided into increments of 5, 10, 15, 20, and 25 centimeters. The first plotted line representing low light treatment is formed by connecting the following points: (2,2), (4,5), and (6,6). The second plotted line representing the control or medium level light treatment is formed by connecting the following points: (2,6), (4,9), and (6,12). The third plotted line representing high light treatment is formed by connecting the following points: (2,8), (4,15), and (6,20).

Point and line graphs also can be constructed from an appropriate data table with Microsoft© Excel as well as with thumbtacks and string on a piece of cardboard.

Bar Graph

Experimental data can also be presented as a bar graph. In the bar graph, the dependent variable, or what is being measured, is still represented by the y-axis. The x-axis or independent variable, indicates treatment categories, which can be qualitative, descriptive, or quantitative.

In the example above, a bar graph can be made with the data from each point in time, such as the maximum stem growth in centimeters after 2, 4 and 6 days. The bars are filled to represent the different treatments. As in the point and line graph, the bar graph allows the relationship between the treatment and its effect to become visually evident. It also frames the results in an understandable context.

To construct a bar graph, put an appropriate scale for the dependent variable on the y-axis. Then choose a color or texture for bars representing each treatment at particular time points, if necessary. Remember, if different colors are being used, do not put red and green next to each other if a student is color blind. See the example in Figure 6.3.

Figure 6.3 Bar Graph

Effect of Light Levels on Sunflower Seedling Height
The x-axis, denoting time, is divided into areas representing 2, 4, and 6 days. The y-axis, denoting seedling height, is divided into increments of 5, 10, 15, and 20 centimeters. Three adjacent bars, each with a different texture or fill pattern for each of the treatments is presented for each of the three time points in the following order: low, medium, and high light. At 2 days, the level of the three bars is 2, 6, and 8 centimeters. At 4 days, the level of the three bars is 5, 9, and 15 centimeters. At 6 days, the level of the three bars is 6, 12, and 20 centimeters.

Bar graphs can be prepared with regular, bold-line, or embossed graph paper. Students with low vision can use a variety of bright colors to fill in the bars to represent different treatments. Students who are blind can prepare collages on sturdy embossed graph paper with textured materials in order to represent the different treatments. In either case, students need to remember to include a key to explain what the colors or textures mean, or label the bars directly. Microsoft© Excel will create bar graphs from appropriate data sets.

Circle or Pie Graph

The circle or pie graph is useful for data sets in which the independent variable is descriptive and the dependent variable can be expressed as a percentage.

For example, a quick survey can illustrate what the eighth grade class ate for breakfast this morning. The descriptive categories, or independent variables, could include cereal, eggs, waffles, pancakes, or nothing at all.

To find the percentages for each of the categories, divide the number of students that fit each category by the total number of students.

To construct the circle graph, the percentages need to be expressed as angles that fill a complete circle. To find each angle, multiply each percentage by the total number of degrees in a circle, or 360. These angles represent the dependent variables. A complete set of data detailing all of these calculations is shown in Table 6.4, and the corresponding pie chart in Figure 6.4.

Table 6.4

Breakfast food of students in 8th grade class

Breakfast	# students	fraction	percentage	degrees
eggs	3	3/20	15%=0.15	54
cereal	7	7/20	35%=0.35	126
waffles	4	4/20	20%=0.20	72
pancakes	2	2/20	10%=0.10	36
nothing	4	4/20	20%=0.20	72

Figure 6.4 Pie chart of data in Table 3

Breakfast Food of Students in 8th Grade Class
A circle is shown that is divided into 5 sections corresponding to the percentages of students in the 5 categories. Cereal is the largest category at 35 percent, waffles and nothing at all are the second largest categories, both at 20 percent, eggs is the next largest at 15 percent, and pancakes is the smallest category at 10 percent.

After drawing a complete circle, use a protractor to measure and draw each angle in the circle graph. Choose a color or texture for each category, and be sure to label each piece of the "pie" or provide a key to explain what each color or texture means.

Students who are blind can use Quick-Draw Paper from APH to prepare raised-line circles with a protractor or an inverted cup or drinking glass. Lines drawn with a medium to thick water-based marker will swell and create a tactile image on this paper. Boundary lines for the angles can be drawn the same way with a protractor or ruler. Ordinary protractors may be difficult to use for a student with a visual impairment. Tactile protractors available from APH, HP, and RNIB are appropriate for use by all students. Microsoft© Excel will create circle or pie graphs from appropriate data sets.

Making Tactile Graphs for Students Who Are Visually Impaired

Histograms, point and line graphs, bar graphs, and pie graphs can be prepared using the following materials:

• APH Bold-line graph paper
• APH embossed graph paper
• APH Quick-Draw Paper and water-based markers
• APH self-adhesive point symbol stickers
• LHS Histogram board with self-adhesive tactile markers
• Metal cookie sheet and magnets
• Cardboard sheets, string, and thumbtacks
• Microsoft Excel Program
  • Print enlarged and color contrasting graph for low vision students
  • Print graph on microcapsule paper for students who are blind, and put through image enhancement machine as follows:

Diagrams printed onto microcapsule paper will become tactile images after enhancement with a TIE (Tactile Image Enhancer), PIAF (Pictures in a Flash), or Swell-Form machine. See contact information for these devices below:

Humanware Pulse Data
175 Mason Circle
Concord, California 94520
800-722-3393
www.humanware.com
This company sells a tactile graphic making device called Pictures in A Flash (PIAF) and microcapsule paper.

American Thermoform Corporation
1758 Brackett Street
La Verne, California 91750
800-331-3676
www.americanthermoform.com
This company sells the Swell-Form machine and Swell-Touch paper (microcapsule paper) for making tactile graphics.

Repro-Tronics, Inc.
75 Carver Avenue
Westwood, New Jersey 07675
800-948-8453
www.repro-tronics.com
This company offers the Tactile Image Enhancer (TIE) and Flexi-Paper (microcapsule paper) for making tactile graphics.

An Experimental Query

It's always nice to have fresh cut flowers last as long as possible. What's the best additive to put in the water to extend the life of the flowers? To test this, collect several identical vases, pour the same amount of water in them, and label each one with a treatment listed in the table below. Add each treatment to the water, stir to dissolve if necessary, and place one or the same number of the same kind of flowers in each vase. Then determine the number of flowers remaining fresh and unwilted per treatment on each subsequent day. This will identify the treatment that allows the most flowers to last for the longest period of time. Table 6.5 shows how the data can be collected.

Table 6.5

The Effect of Additives on the Life Span of Cut Flowers

Number of flowers still fresh on the following days:

Treatment	Day 1	Day 2	Day 3	Day 4	Day 5	Day 6
Water Alone
Penny
5g sugar
5g salt
10ml 7Up®

Identify the following concepts for this experimental protocol:

• Hypotheses
• Control treatment
• Experimental treatments
• Dependent variable
• Independent variable(s)

Answer the following questions about the same data set:

• Which graphing method(s) would best present the data?
• Why is the same type of cut flower paced in each vase?
• Why are separate vases for each additive needed?
• Why is a vase with just water and no additive included?
• Would it matter if the penny were old or new?
• Form additional hypotheses that test different amounts of sugar, salt, 7Up^®, pennies, etc. added to the vases
• What other additives could be tested?
• Could the additives be tested for a longer or shorter period of time?

Writing a Good Lab Report

The exact format of a laboratory report will vary according to a particular instructor's requirements, but the basic components are usually the same. A descriptive list of the components of a comprehensive report follows:

Cover or Title Page

This page highlights the title of the investigation, and includes the name of the researcher(s), the date the report is due, and the name of the instructor.

Title

The title is a sentence that describes the main point of the investigation, often including the experimental situation. For example, "The effect of different colored light on the growth of Coleus plants," or "Population changes of Daphnia pulex under acid stress."

Abstract

The abstract is a short paragraph that briefly explains the purpose of the experiment, lists the results, and their interpretation. Experimental methods are usually not included unless they are unique and part of the purpose of the experiment. The most basic information is given in this part of the report.

Introduction

This part explains in detail the purpose and justification of the experiment(s). The hypotheses to be tested are explained along with information from other sources that support the working hypothesis, such as observations, references to the literature, and personal communications. The big picture is also included, that is, how the question of interest fits into, or has an impact on the real world.

Materials and Methods

All items needed to perform the experiment can be simply listed in this section. A more formal report may require their presentation in paragraph form. This is followed by a complete description of the experimental procedure, identifying the control and experimental treatments, and all variables to be tested. Sometimes it's helpful to include a diagram for clarification. The materials and methods should be complete enough so that another scientist or student could perform the same experiment in the same way in his laboratory.

Results

This section of the report details what happened during the experiment, but does not interpret or analyze these events. The results of an experiment are the effects of a particular treatment and produce data, which are often in the form of numbers and measurement units. Results can also be in the form of a description, as in the case of qualitative changes such as color.

It is most convenient to present data in the form of a table or graphic such as a bar graph, point and line graph, histogram, or pie chart. The relationships between the cause or treatment, and effect or result, are more easily observed and understood when they are displayed in this way. All tables and graphs must be properly labeled including the title, x- and y-axes, and keys, if necessary. Illustrations and photographs are also appropriate ways to document experimental results, particularly for qualitative changes in experimental groups.

If possible, prepare the data collection sheet in advance, making columns and rows for the treatments or independent variables as well as the effects or dependent variables. Tables are then easily converted to graphic representations. The type of graph to make will depend on the experimental situation and the data it generates.

All graphs and tables of data generated by the experiments must be accompanied by written descriptions of these results.

Discussion and Conclusions

This section is reserved for the interpretation and analysis of the results of the experiments. In other words, what do the results mean in a broader sense than just describing them? Remember that a proper experiment is controlled, and treatments test the effect of one variable at a time, creating a somewhat artificial situation. In order for the data to have meaning, they need to be related to the real world and why the experiment was done in the first place. Topics to discuss can include the following:

• Do the results support or not support any of the hypotheses presented in the introduction? Recall that proper experimental design demands that predictions be made before the experiment is conducted.
• How do the results fit in the context of the real world? How artificial were the experimental conditions?
• Can the results be applied to a practical situation?
• Can a pattern be identified from the data?
• Can a concrete or mental model be constructed from the observed data or trends?
• Can predictions be made for other situations, either hypothetical or real?
• How do these experiments compare to experiments testing similar or related hypotheses?

References or Bibliography

All sources of information that were used to inform the laboratory report in any way must be listed in this section. Information sources include books, periodicals, journals, websites, and reference manuals such as encyclopedias. They should be listed in alphabetical order by the first or primary author. There are many correct formats in which this information may be presented; consult the APA stylebook, the Chicago Manual of Style, or look at published research reports to see other reporting styles.

Appendix

APH
American Printing House for the Blind
1839 Frankfort Ave
P.O. Box 6085
Louisville, KY 40206-0085
1-800-223-1839
www.aph.org

AM
Ann Morris
P.O. Box 9022
Hicksville, NY 11802-9022
1-800-537-2118
FAX: 516-937-3906
http://www.annmorris.com

BAS
Bel-Art Scienceware
6 Industrial Road
Pequannock, NJ 07440
1-800-423-5278
FAX: 973-694-7199
http://service.belart.com/

CB
Carolina Biological
2700 York Road
Burlington, NC 27215
1-800-334-5551
http://www.carolina.com/general/directories/site_map.asp

DE
Delta Education
80 Northwest Blvd.
P.O. Box 3000
Nashua, NH 03061-3000
1-800-258-1302
FAX: 1-800-282-9560
http://www.delta-education.com

DL
Dynamic Living
428 Hayden Station Road
Windsor, CT 06095-1302
1-888-940-0605
FAX: 860-683-2694
www.dynamic-living.com

ES
Edmund Scientific
Consumer Science Division
60 Pearce Avenue
Tonawanda, NY 14150-6711
1-800-728-6999
FAX: 1-800-828-3299
www.scientificsonline.com

FLN
Flinn Scientific, Inc.
P.O. Box 219
Batavia, IL 60510
1-800-452-1261
FAX: 1-866-452-1436
http://www.flinnsci.com

FRE
Frey Scientific
P.O. Box 1801
100 Paragon Parkway
Mansfield, OH 44903
1-800-225-3739
FAX: 1-877-256-3739
http://www.freyscientific.com

HSB
Hadley School for the Blind
700 Elm Street
Winnetka, IL 60093
800-323-4238
www.hadley-school.org
HSB offers several distance high school science courses.

HP
Howe Press
Perkins School for the Blind
175 North Beacon Street
Watertown, MA 02472
617-926-2027
FAX: 617-924-3434
www.perkins.org

ILA
Independent Living Aids
P.O. Box 9022
Hicksville, NY 11802-9022
1-800-537-2118
FAX: 516-937-3906
www.independentliving.com

LHS
Lawrence Hall of Science #5200
University of California
Berkley, CA 94720
1-510-642-5132
FAX: 1-510-642-7387
www.lhs.berkeley.edu/cml/saviselph.html

LSI
The Laboratory Safety Institute
192 Worcester Road
Natick, MA 01760
508-647-1900
FAX: 508-647-0062
http://www.labsafety.org

LS & S
LS & S, LLC
P.O. Box 673
Northbrook, IL 60065
1-800-468-4789
FAX: 1-800-498-1482
TTY: 866-317-8533
www.lssproducts.com

MA
MaxiAids
42 Executive Blvd.
Farmingdale, NY 11735
1-800-522-6294
FAX: 631-752-0689
TTY: 1-800-281-3555
www.maxiaids.com

NFB
National Federation of the Blind
1800 Johnson Street
Baltimore, MD 21230
Phone: 410-659-9314
FAX: 410-685-5653
Email: nfb@nfb.org
www.nfb.org
NFB National Center for Blind Youth in Science will offer a web "portal" that will serve as a comprehensive source of information and resources for science teachers of visually impaired students; see the following link for future updates:http://nfb.org/nfbji/science.htm

RNIB
Royal National Institute for the Blind
105 Judd Street
London WC1H 9NE
44 20 7391 2318
Tel: 020 7388 1266
Fax: 020 7388 2034
www.rnib.org

SC
SightConnection
9709 Third Ave. NE, #100
Seattle, WA 98115-2027
1-800-458-4888
www.sightconnection.com

SK
Science Kit & Boreal Laboratories
777 E. Park Drive
P.O. Box 5003
Tonawanda, NY 14150
1-800-828-7777
FAX 1-800-828-3299
http://www.sciencekit.com

SW
Sargent-Welch VWR International
P.O. Box 5229
Buffalo Grove, IL 60089-5229
1-800-727-4368
FAX: 1-800-676-2540
www.sargentwelch.com

VER
Vernier Software & Technology
13979 SW Millikan Way
Beaverton, OR 97005-2886
1-888-837-6437
FAX: 503-277-2440
http://www.vernier.com/

WNS
Ward's Natural Science
P.O. Box 92912
Rochester, NY 14692-9012
1-800-962-2660
www.wardsci.com

References

Alldred, N. D. & Haberer, S. (2001). Science Skills Handbook. Cincinnati: Centre Point Learning, Inc.

Berda, M. & Blaisdell, M. J. (1998). Science Projects for all Students; NY: Facts on File.

Brasher, T. (1995). Elementary Physics with Activities. Revised. Orlando, Florida: Harcourt Brace & Company.

Campbell, N. A. & Reece, J. B. (2002). Biology: Concepts and Connections. San Francisco, CA: Benjamin Cummings.

Dickerman, J. (2000). Investigating Biological Concepts. A Laboratory Manual; Englewood, CO: Morton Publishing Company.

Gevers, M. S. & Murphy, R. (2002). Teaching the Student with a Visual Impairment; Louisville: American Printing House for the Blind.

Gilbert, S. W. & Ireton, S. W. (2003). Understanding Models in Earth and Space Science. Arlington: NSTA Press.

Ruef, K. (1998). The Private Eye^® (5X). Looking/Thinking by Analogy. Seattle: The Private Eye Project.

Silberberg, M. (1996) Chemistry. The Molecular Nature of Matter and Change. St. Louis: Mosby-Year Book, Inc.

VanCleave, J. (1990) Biology for Every Kid. New York: John Wiley & Sons, Inc.

VanCleave, J. (1991) Earth Science for Every Kid. New York: John Wiley & Sons, Inc.

VanCleave, J. (1995) The Human Body for Every Kid. New York: John Wiley & Sons, Inc.

Index

A
Abstract
  lab report
accessibility
accommodations
  technological
Acid
  mixing
acidity
adaptations
  general
  for measuring
Advance Preparation Checklist
alkalinity
aprons

B
balance
  practical use
  adaptations
  electronic
  SAVI/SELPH
  triple-beam
Bar Graph
  when to use
  construction
base
  mixing
Beakers
Bibliography
  lab report
Biology
  models
blindness
Bottle Top Dispenser
Braille labels
Bunsen Burner
  precautions
  safety

C
Calculator
  accessible graphing
CCTV
  Access
  Definition
chemicals
  handling
  mixing
  MSDS
  smelling, wafting
  weighing
chemical reactions
  non-visual demonstrations
Chemistry
  models
Circle or Pie Graph
  when to use
  construction
clock
  analog
  atomic
  digital
closed-circuit television
Colorimetric methods
  litmus paper
  pH indicator strips
Compound Microscope
  care
  specimen preparation
Conclusions
  lab report
Cooling

D
data collection
Density
  definition
  of liquids
dependent variable
  definition
Discussion
  lab report
dissecting microscope
Dissection

E
Earth Science
  models
experiment
  controlled
Experimental Design
Ex Officio Trustee
eyestrain
  from light sources
  with monocular microscope

F
Federal Quota Program
Frequency Diagram
  when to use
  construction
fume hood

G
glare
gloves
goggles
graphs
  bar
  circle
  histogram
  pie
  point and line
graph paper
  bar graphs
  bold-line & embossed
  histograms
  making tactile graphs

H
Hazards
  electrical
  mechanical
  temperature
Heating
Histogram
  when to use
  construction
Hot plate
Hypothesis
  formation
  testing

I
Increasing Contrast
independent variable
  definition
instruments
  dissecting
International System of Units
ISU

L
Lab report
  how to write
Labels
  braille
  for microscope
  hazardous chemicals
  preparation
lab ware
legally blind
length
  measurement
Lighting
  fluorescent
  incandescent
liquid level indicator
Litmus Paper
Low vision

M
Magnetic Stirrers
Mass
  measurement
Material Safety Data Sheet
Measurements
  quantitative
Meniscus
Meter Tapes
microcapsule paper
  graphing
  tactile images
  tactile graphs
Microscope
  activities
  compound
  dissecting
  eyestrain
  videomicroscopy
Model
  abstract
  concrete
  functional
  scale
Modeling Materials
MSDS
  format

O
optical devices

P
pH
  measurement
Physics
  models
pH Indicator Strips
pH Meter
  benchtop
  portable
PIAF
  definition
  tactile images
  tactile graphs
Pipets
pipettors
point-and-line graph
  when to use
  construction
protractor

R
Rulers

S
Safety
  attire
  general
  personal
  preparing solutions
scale
  spring
  talking kitchen
Science
Scientific Method
  steps
Skills Checklist
Slides
  Deep well
  permanent
solute
Solution
  final volume
  preparation
solvent
Stereomicroscope
  care
  specimen preparation
stirring bars
Stirring liquids
Stirring rods
String
Swell-Form machine
  tactile diagrams
  tactile graphics
  tactile graphs
Syringes

T
tactile diagrams
  preparation
  graphics
  graphs
Tactile Graphics
Tactile Graphs
construction and preparation
  general
  histogram
  point & line
  bar graph
  circle or pie graph
  materials
TAEVIS
talking color detector
Talking Measuring Jug
Temperature
  measurement
Thermometer
  Celsius
  Fahrenheit
  Glass
  glass-free
  SAVI/SELPH
  steel probe
  Talking
  unbreakable
TIE
  tactile images
  tactile graphs
time
Trundle Wheel

V
Videomicroscopy
visually impaired
visual impairment
  definition
Volume
  measurement
  displacement method
  measured with balance

W
waste receptacles
weight
  measurement
Wet Mounts

Adapting Science for Students with Visual Impairments

Advance Preparation Checklist

Catalog Number: 7-00001-00

        © 2006

Name ________________________________

Course Title ___________________________

Instructor _____________________________

Date _________________________________

The Advance Preparation Checklist is designed to be used in conjunction with "Adapting Science for Students with Visual Impairments; A Handbook for the Classroom Teacher and Teacher of the Visually Impaired," and the accompanying Skills Checklist. These materials provide suggested items for use, and the abbreviations for the vendors from which they can be obtained. Consult the Appendix in the handbook for details about the suggested vendors.

Adapting Science for Students with Visual Impairments
Copyright © 2006, American Printing House for the Blind, Inc. Louisville, KY 40206-0085
All rights reserved. Printed in the United States of America

This publication is protected by Copyright and permission should be obtained from the publisher prior to any reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise.

For information regarding permissions, write to:
American Printing House for the Blind, Inc.
Resource Services
1839 Frankfort Avenue
Louisville, KY 40206-0085

Advance Preparation	Behavior Present? Yes/No	Date Student Informed	Date Behavior Addressed
Behaviors particular to students who are blind or visually impaired:
a. Bringing objects close to eyes
b. Eye rubbing and poking
c. Finger sniffing
d. Rocking body back and forth
e. Tasting substances
f. Using touch to determine levels of solids and liquids
g. Other
	Needed before course begins? Yes/No	Date in progress	Date completed
Familiarization with experimental procedure(s):
a. Read through all steps and protocol
b. Practice operations; see Skills Checklist
c. Identify needed adaptations; see Skills Checklist
d. Other
Organizational tray for devices & lab ware:
a. Ordinary cafeteria style tray
b. Metal tray from CB
c. Sorting tray from LHS and APH
d. Other
Lab ware and equipment stabilization
a. Clamps
b. Larger containers
c. Support stands
d. Other
Lighting Considerations
a. Change overhead lighting to warm incandescent bulbs
b. Natural light from window
c. Task Lamp
d. Other
Location of Safety equipment and supplies
a. Apron
b. Eyewash
c. Fire alarm
d. Fume hood
e. Gloves (latex, pvc, Kevlar®)
f. Goggles
g. MSDSs
h. Other
Magnification devices; see Skills Checklist
a. Compound Microscope
b. CCTV
c. Dissecting Microscope
d. Hand-held magnifier
e. Stand magnifier
f. Other
Orientation in room/laboratory
a. Chemicals and supplies
b. Desk/lab station
c. Exits
d. Safety Equipment
e. Waste receptacles
Other
Clean-up considerations:
a. Latex/pvc gloves Note: Gloves may decrease tactile sensitivity
b. Waste disposal
• Glass
• Preserved organisms
• Acids & bases

Adapting Science for Students with Visual Impairments

Skills Checklist

Catalog Number: 7-00001-00

        © 2006

Name ________________________________

Course Title ___________________________

Instructor _____________________________

Date _________________________________

The Skills Checklist is designed to be used in conjunction with "Adapting Science for Students with Visual Impairments; A Handbook for the Classroom Teacher and Teacher of the Visually Impaired." The page numbers listed in the first column of the checklist refer to where information for the topic in the corresponding row can be found in the handbook. The handbook provides suggested items for use, and the abbreviations for the vendors from which they can be obtained. Consult the Appendix in the handbook for details about the suggested vendors.

Adapting Science for Students with Visual Impairments
Copyright © 2006, American Printing House for the Blind, Inc. Louisville, KY 40206-0085
All rights reserved. Printed in the United States of America

This publication is protected by Copyright and permission should be obtained from the publisher prior to any reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise.

For information regarding permissions, write to:
American Printing House for the Blind, Inc.
Resource Services
1839 Frankfort Avenue
Louisville, KY 40206-0085

Skills Checklist	Page	Skill Needed	Date Skill Achieved	Type of Magnifier Needed	Identify Adaptation Needed
Dissection	40
a. Instrument identification	40
b. Magnification	40
• CCTV	40
• Dissecting microscope	36
• Stand magnifier	40
• Other
c. Other
Force	46
a. Knows definition
b. Performs measurement	46
c. Other
Length	42
a. Knows definition	42
b. Length measurements
• Meter tapes and rulers	42
• String	43
• Trundle Wheel	43
• Other
c. Other
Liquid Measurement	49
a. Consider before dispensing liquids:	50
• Fullness of source bottle	50
• Does the measuring device:
• Fit the mouth of the source
• Reach the liquid level of the source bottle?
• Pour a small amount from the source bottle into another container	50
• Detects meniscus	50
• Other
b. Performs volume measurements:
• Beakers	52
• Bottle top dispenser	54
• Graduated cylinders	51
• Graduated pipets	54, 55
• Syringes	52, 53
• Talking Jug	54
• Pipettors	54, 55
• Measuring volume by mass	56
c. Other
Making Solutions	18
a. Magnetic stirrer/magnetic stirring bar	56
b. Stirring rod	56
c. Knows when solid is dissolved
d. Other
Mass	43
a. Knows definition	43
b. Consider before measuring dry chemicals:	47
• Fullness of source jar
• Size of spatula versus size of jar mouth
• How far the jar must be tilted to scoop out chemical
• Ability of student to maintain spatula contents
• Ability of student to completely empty spatula and weighing container
• Other
c. Performs mass measurements
• Double cup balance	44
• Electronic digital scale	46
• Spring scale	46
• Talking scale	47
• Triple beam balance	45
• Other
d. Other
Microscopy
a. Care of the microscope	34, 35
b. Compound Microscope
• Understands parts	33
• Prepares wet mounts	38, 39
• Views permanent slides or wet mounts	38, 39
• Other
c. Dissecting Microscope	36
• Understands parts	36
• Views objects on stage	38
• Other
d. Microvideo Camera	37
• Understands parts	37
• Computer image capture	37
• Views slides on compound microscope	37
• Views slides on dissecting microscope	37
e. Other
pH	62
a. Knows definition	62
b. Performs pH measurements
• Litmus paper	64
• pH test strips	64
• pH meter	63
• Other
c. Other
Temperature	57
a. Knows definition
b. Performs temperature measurements	58
• Glass thermometer	58
• Glass-free thermometer	58, 59
• Talking thermometer	58
• Other
c. Performs cooling operations	58
• Dry ice	58
• Freezer	58
• Ice Bath	58
• Refrigerator/Freezer	58
• Other
d. Performs heating operations	58
• Bunsen Burner	60
• Hot Plate	62
• Other
e. Other
Time	57
a. Performs time measurements	57
• Analog clock/timer	57
• Atomic clock	57
• Digital clock/timer	57
• Other
Units of Measurement
a. Metric vs. Imperial	40
b. Table of Metric & Imperial equivalents	67
c. Table of Metric Units	41
d. Other
Volume	47
a. Knows definition	47
b. Performs liquid volume measurements
• Beakers	52
• Bottle top dispenser	54
• Graduated cylinders	51
• Graduated pipets	54, 55
• Measuring volume by mass	56
• Pipettors	54, 55
• Syringes	52, 53
• Talking Jug	54
• Other
c. Determines volume of an object
• Geometrically shaped	47
• Large objects	48
• Small objects	48
• Other
d. Other
Weight	43
a. Knows definition	44
b. Performs weight measurements
• Double cup balance	44
• Electronic digital scale	46
• Spring scales	46
• Talking scales	47
• Triple beam balance	45
• Other
c. Other