In the Classroom
Chemistry for the Visually Impaired Judy L. Ratliff Department of Chemistry, Murray State University, P.O. Box 9, Murray, KY 42071-0009 The chemistry experience for visually impaired students tends to be devoid of the exercises, experiments, and demonstrations generally considered necessary to aid in the development of a clear, conceptual understanding of the principles examined in a typical introductory class. To a visually impaired student interested in and excited by chemistry, the extra time and effort required to approximate the experience of sighted students is accepted willingly. However, to a general education student with just enough interest to sign up for an introductory course that already contains a large number of semi-interested sighted students, the desire to accept the additional effort required is not present. To provide a more valuable experience for these students in a general education or introductory chemistry class, a few modifications can be made that will allow them to participate productively. Demonstrations for the visually impaired in a chemistry class require additional thought but can be accomplished with a little extra effort. Vivid descriptions of elements, reactions, and processes are necessary when teaching visually impaired students. In thoroughly describing such processes to accommodate impaired students, sighted students are assisted in developing mental pictures of what is going on as well. I teach a Consumer Chemistry class and was fortunate enough to have a visually impaired student enroll in it last semester. The class had an enrollment of 70 students and I found that I used the chalk board less and relied more on physical objects that were passed around during the lecture period. A good example of this is how the course begins by discussing the elements, their differences and similarities. This discussion moves us into the laboratory, where we examine the density of different substances.
electrolytes and nonelectrolytes I generally use testers constructed from a film canister as described by Gadek (2). To adapt this to my visually impaired student I connected a buzzer in the place of the LED. The visually impaired student was then able to explore the selected samples as sighted students do. Visually impaired students can be given the mini-conductivity-tester with their reagents, labeled in braille, and asked to complete the exercises, while sighted students use the LED mini-conductivity-testers. Visually impaired students then require no more guidance or assistance than sighted students.
Construction of Apparatus The conductivity tester cost less than $4.00. It is easy to assemble and very rugged, and provides a great deal of entertainment for sighted and nonsighted students. To construct the tester the following parts were obtained: (i) an empty film canister (free from the local 1-hour photo mart); (ii) a 9-volt battery (2 for $1.00 at the Dollar Store); (iii) a 9-volt battery cap (5 for $1.89 at Radio Shack); (iv) a 200– 300-Ω resistor (a five pack of 220-Ω resistors cost 49¢); (v) 1.5–3-V DC minibuzzer, catalog no. 273-053A from Radio Shack, $2.59; (vi) 2 pieces of wire approximately 10 cm long. The total cost was $3.57 per tester, excluding the cost of the connecting wires and taxes. Connect the assembled items as shown in Figure 1. To secure the connections, I would suggest that you solder them, but before soldering make sure your tester works. If it does not, switch the wires by which you connected to the buzzer.
Density
Battery cap
For the visually impaired student to examine the density of an object I made sure that her station had a ruler with raised graduations and a triple beam balance. The use of a triple beam balance by visually impaired students has been described by Hiemenz and Pfeiffer (1) (A talking balance would be nice, but expensive, and could not be justified by one student taking a class one semester.). The ruler was cheap, 10¢ at the local Dollar Store, and the balance was in a storage room. The visually impaired student was instructed how to use the ruler with her fingernail and how to count the weights on the balance. The density of irregular objects was found using water displacement to measure volume. A container was filled to overflowing with water then carefully moved over a preweighed, dry pan. The irregular object was then dropped carefully into the water, displacing a volume equal to its own. The displaced volume was then weighed and converted to a volume using the density of water. Conductivity
– Battery
Resistor
Buzzer
Figure 1. Diagram for the assembly of the electrolyte tester. Once the parts are secured, wrap the wires around the battery and insert it into the film canister. Cut a hole in the top of the canister lid to allow the buzzer to pop through; then punch 2 additional holes, one for each loose wire.
Once you are sure the device works, wrap the majority of the wires around the battery and insert it into the film canister. Punch two holes in the canister lid for the loose ends of the wires to poke through, then cut one to allow the buzzer head to fit through. Finally, place the lid on the canister and secure it, if you wish, with electrical tape. The explanation of how to construct this tester consumes more time than actually doing it.
To examine the conductivity of metals and nonmetals,
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In the Classroom Discussion These are just two examples of how general chemistry labs can be made accessible to visually impaired students at relatively low cost. No waivers of lab requirements are necessary and a large amount of additional class preparation is not needed. The most troublesome problem encountered for the student during the semester was the unavailability of a brailled text book. If a student has a burning desire to become a chemist and happens to be visually impaired, he or she is highly motivated and more driven to
overcome difficulties in labs—for example, spending extra time working out ways to titrate using weight differences or conductimetric differences in analyte solutions as described by Tallman (3). These concepts are beyond most general education students, let alone visually impaired general education students. Literature Cited 1. Hiemenz, P. C.; Pfeiffer, E. J. Chem. Educ. 1972, 49, 263–265. 2. Gadek, F. J. J. Chem. Educ. 1987, 64, 628–629. 3. Tallman, D. E. J. Chem. Educ. 1978, 55, 605–606.
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