In the Classroom edited by
Safety Tips
Timothy D. Champion Johnson C. Smith University Charlotte, NC 28216
Introducing Safety Topics Using a Student-Centered Approach Steven M. Wright Department of Chemistry, University of Wisconsin–Stevens Point, Stevens Point, WI 54481;
[email protected] In his column, Teaching and Training Chemical Health and Safety, Gottschall asks, “how can we best teach safety?” (1). After all, teaching strategies are moving away from lecture format to more inquiry-based, cooperative approaches. Gottschall jokes that using the experiential approach to teaching safety may not always be desirable. Bondeson and coworkers (2) help us to understand this better. They classify the content of chemistry courses into four groups: data, models, techniques, and conventions. Safety issues are generally classified as technique or convention. Proper handling of hazardous chemicals or the use of emergency equipment, like an eyewash fountain, are techniques. Bondeson suggests that techniques are effectively learned by demonstration and practice and are not necessarily well suited for inquiry, discovery-based learning. Methods of communication, like material safety data sheets or chemical bottle labeling systems are conventions. Repetitive practice is offered as an effective learning strategy for conventions. While this does not bode well for student-centered approaches to safety training, instructors still search for cooperative activities that teach safety and engage students. For example, Helser (3) uses a laboratory-equipment scavenger hunt, in which student groups must cooperate to locate safety equipment. In this article, I offer three activities that introduce topics of chemical health and safety using student-centered, cooperative methods. These activities were developed and used in polymer workshops for elementary and secondary instructors. They have been field-tested in university introductory chemistry classes. Note that each of these activities introduces a convention. Simply stated, the constructivist model of knowledge can be summarized as: “Knowledge is constructed in the mind of the learner”(4). Using a constuctivist’s teaching strategy, conventions can be effectively taught by first asking students to develop their own convention. Students use their prior knowledge to develop a convention; presumably, their convention makes sense to them. The instructor then adds parameters and asks questions that guide students toward an understanding of the convention commonly used. With this approach, students recognize that the convention is the result of rational thought, not just arbitrary rules. The convention is more likely to be meaningful to the students, and thus more easily remembered and used. The Four Pests This activity introduces students to material safety data sheets (MSDS) and labeling of hazardous chemicals. I tell my students that we have been asked by the Wisconsin Department of Tourism to communicate the hazards of four www.JCE.DivCHED.org
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pests commonly found in Wisconsin. Students are divided into groups and asked to create a method of communicating the hazards for the bumblebee, mosquito, deer tick, and deer fly. Their task is to determine three things: first, to whom do we communicate; second, what do we communicate; and third, how do we communicate. After several minutes working together the groups are asked to report on their ideas. While the specifics vary, their ideas can usually be easily classified. To whom do we communicate? Groups suggest that either all people in the state be told about the hazards of the pests, or only those people likely to come in contact with the pests be told. What do we communicate? Groups often suggest a quick identification of the pests and a bit about the hazard—sting, itch, Lyme disease—or a detailed description of the pest and its hazards. How do we communicate? Groups usually suggest an oral warning—by radio, television, or park ranger—or written warning—pamphlet or newspaper. After I have grouped the ideas into these categories, I give the students an additional parameter; we need to communicate as efficiently as possible, in order to hold down costs. With this additional parameter, the whole class quickly suggests that we target only “high risk” people, that is, the people on lakes and in the woods. Students suggest that we hand out pamphlets to each person entering a high-risk zone and that these pamphlets include a means to identify the pest and its general hazard. Students recognize the limitations of the brief information given on the pamphlet and suggest that we keep detailed documents about the pests and their hazards at strategic locations, like ranger’s cabins and hospital emergency rooms. At this point, I ask them to think about effective ways to communicate the hazards of chemicals used in the lab. Very quickly, students suggest we initiate a brief way to communicate the identity and general hazards of the chemical to people in the laboratory, with a detailed document in some strategic location. We then discuss material safety data sheets—detailed documents outlining the properties of hazardous chemicals (5) that may be found on file in our stockroom and online—and our labeling system for hazardous chemicals—a quick, nontechnical summary that reminds people in the laboratory about the hazards of a chemical. The Nastiest Chemical This activity is designed to help students begin to understand the complementary nature of hazardous chemical labeling systems and MSDSs. Additionally, students will often discover that more than one labeling system exists and, hopefully, they will begin to differentiate between systems like the National Fire Protection Association’s (NFPA) labeling system, the National Paint and Coatings Association’s
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In the Classroom
Hazardous Material Identification System (HMIS), and the American National Standards Institute’s (ANSI) Standard for Hazardous Industrial Chemicals—Precautionary Labeling. I try to do this activity soon after the Four Pests activity, so students have already been introduced to MSDSs and labeling systems, and thus they can continue to construct understanding about these systems using their prior knowledge. I ask students to form several groups and give each group an MSDS for a particularly hazardous chemical. (I try to choose very hazardous chemicals for dramatic effect.) Each group must read through the MSDS and find ways to convince the rest of the class that their substance is the most hazardous chemical of all those assigned. As novices, my students have some difficulty reading through the MSDS and almost always look for an overall rating for the chemical like an ANSI signal word, or an HMIS or NFPA rating (6). Some students might be confused by the signal words Warning or Danger as found on their MSDS and wonder whether these words communicate specific hazards. This provides a teachable moment to discuss ANSI’s standards for the use of signal words on labels of hazardous chemicals and the specific characteristics those words communicate (7). Another group of students might argue that hydrogen gas is more hazardous than ethyl alcohol because hydrogen has a 4-flammability rating (according to the NFPA rating) while ethyl alcohol’s HMIS flammability rating is 3. This provides opportunity to distinguish between the NFPA diamond, which is intended to provide information about potential hazards when the material is in a fire (8), and the HMIS system, which provides a concise summary of the hazards associated with the use of a hazardous chemical. Still other groups might argue that chlorine and nitric acid are equally hazardous because they each carry an HMIS health rating of 3. When asked if the health hazard of these two chemicals is exactly the same, students can learn the specific details communicated by an HMIS rating of 3 (9), as they are encouraged to go back to the MSDS for more information. Hopefully, the point is understood. Hazardous materials labeling systems are intended as brief reminders of a chemical’s hazards, while the MSDS provides valuable details about the chemical’s handling, storage, and use. Even though reading and understanding an MSDS may be difficult, extracting useful information is crucial (10, 11). Which Is the Best Solvent? To help students remember the conventions used on MSDSs and hazardous chemical labeling systems, some practice and repetition are necessary. I offer this activity as an example of a “follow-up” to reinforce and build upon students’ prior understanding of MSDSs. In this lesson, students begin to understand that safety and disposal are important factors to consider when decisions about laboratory procedures are made. During our unit on polymer chemistry, we try to distinguish between dissolving a polymer and swelling a polymer. To initiate discussion, a demonstration is performed to seek the answer to the question, which is the best solvent for dissolving polystyrene foam (Styrofoam): acetone, toluene, or methylene chloride. Acetone only swells the polymer, so it is eliminated immediately. Both toluene and methylene chloride will dissolve Styrofoam, so how do we choose which is 1520
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better? With some prodding students recognize safety and disposal as important considerations when choosing a chemical to do a job. Student groups are formed, MSDSs are distributed, and the student groups refer to MSDSs to make their judgment based both on ability to dissolve and safety. Concluding Remarks These three activities use teaching methods that introduce aspects of hazard communication using a student-centered approach and a constructivist-teaching perspective. While formal assessment of learning was not carried out, I am pleased that workshop participants (elementary, middle, and high school instructors) considered these exercises valuable enough to modify them and include them in a book of activities that they will publish (12). Both workshop participants and my university students have responded well to these activities. They seem to learn about MSDSs and labeling systems while having some fun. Acknowledgments I would like to acknowledge my friends and colleagues who participated in the Macromolecular Teacher Resource Institute summer workshops. The Institute was supported by the National Science Foundation Teacher Enhancement Grant #ESI-9355608 and the Intersociety Polymer Education Council. Literature Cited 1. Gottschall, W. C. Chemical Health and Safety 1998, 5, 3. 2. Bondeson, S. R.; Brummer, J. G.; Wright, S. M. J. Coll. Sci. Teach. 2002, 32, 182–187. 3. Helser, T. L. J. Chem. Educ. 1999, 76, 68. 4. Bodner, G. M. J. Chem. Educ. 1986, 63, 873–878. 5. Alaimo, R. J.; Walton, L. A. Material Safety Data Sheets. In Handbook of Chemical Health and Safety; Alaimo, R. J., Ed.; Oxford University Press: Oxford, 2001; pp 317–321. 6. Reale, M. J.; Young, J. A. Precautionary Labels and Material Safety Data Sheets. In Improving Safety in the Chemical Laboratory: A Practical Guide, 2nd ed.; Young, J. A., Ed.; John Wiley & Sons, Inc: New York, 1991; pp 7–23. 7. Hazardous Industrial Chemicals-Precautionary Labeling; Document #ANSI Z129; American National Standards Institute: New York, 2000; pp 1–2000. 8. NFPA 704 - Standard System for the Identification of the Hazards of Materials for Emergency Response; National Fire Protection Association: Quincy, MA, 2001. 9. HMIS Home Page. http://www.paint.org/hmis (accessed Jun 2005). 10. Miller, G. J.; Heideman, A.; Greenbowe, T. J. J. Chem. Educ. 2000, 77, 1185–1187. 11. For hazardous chemical information sheets intended for use by chemical educators, see Chemical Laboratory Information Profiles (CLIPs) appearing in this Journal, for example: Young, J. A. J. Chem. Educ. 2001, 78, 444–448. 12. Polymer Activities for Grades 6-9; Droske, J. P., Hall, S., Eds.; POLYED National Information Center: University of Wisconsin-Stevens Point, 2004. http://www.uwsp.edu/chemistry/ polyed (accessed Jun 2005).
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