In the Classroom
The Design and Synthesis of a Large Interactive Classroom Laurel L. Clouston* and Mark H. Kleinman Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, BC V8W 3V6, Canada
In the current academic and financial climate where increasing student enrollment is a reality, many universities have opted to utilize large class sizes as a means of reducing costs. Therefore, it is of much interest to find effective ways to teach a large number of students while adequately addressing a variety of learning styles. To this end, we have developed a convenient method to divide a large class into groups ideally suited for discussion and active learning. In this manner, the important concepts of SN1 and SN2 mechanisms were conveyed to a large group of students in an introductory organic chemistry class. Although this work was conducted in a university setting, a similar exercise could be carried out at almost any level and could be tailored to suit a variety of class sizes. At the University of Victoria (British Columbia, Canada) the number of registered students in the first organic chemistry course averages 100. Using a conventional lecture style, it is virtually impossible to address all of the difficulties encountered by the learners during each teaching episode. It is well documented that cooperative learning aids in student development and increases learning efficiency (1–4), and in recent times, cooperative learning has been employed effectively in chemistry (5–7). By using this type of teaching style we expected that the students would become active learners, thereby facilitating learning the main features of the SN1 and SN2 mechanisms. In the exercise, an overview of the mechanism with its kinetic and synthetic implications was followed by a more detailed examination of the mechanisms through active learning exercises. Before the Class One class prior to the group learning episode, note packets were given out that contained information regarding the nature of the content of the upcoming class. The note packet included a mechanistic summary of the two reactions, assigned reading in the textbook, and a brief description of the activities to be used during the class. In this manner the advance notes served to clarify the learning objectives of the subsequent exercise. Division of the Class Large classes are difficult to divide in a convenient and efficient manner. In larger groups, some participants begin to withdraw from the discussion or ignore the proceedings once the group numbers more than 6 people (3). With this in mind, we divided the class using a pyramid-type structure (Fig. 1). The class was divided into three main groups (A, B, C). In each main groups, two subgroups, SN1 and SN2, were formed. Each of these subgroups was further subdivided into three small groups (1, 2, and 3). In this manner a class of 100 students was quickly divided into groups with 5 or 6 members. Another significant advantage to this pyramid breakdown structure is the ease with which the small groups may be *Corresponding author
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reorganized within the main groups (A, B, C) to permit mixing of subgroups (S N1 and SN2). To avoid wasting valuable class time, it was imperative that the organization of the groups be completed before the lecture. Thus, an assignment sheet (e.g., “ASN1 1”) was given to each student as the students entered the classroom. The desks and chairs had already been placed in circles of 5 chairs to accommodate the groups. Students were directed to the proper chairs so that groups were assembled at the start of the class. Another means of dividing the class would be to distribute the assignment sheets to the empty desks, so that the groups form automatically as the students take their seats. Learning Format The class began with an overview of the forthcoming exercise, which included the rationale behind cooperative learning and the expected learning outcomes. This impact statement helped to alleviate any potential confusion in learners who had yet to encounter this type of teaching or learning. The next 10 minutes were used to introduce the highlights of the two key reactions. The students used this time to add further notes to their handouts, ensuring a clear summary of the concepts. Vital topics such as the difference between intermediates and transition states, the types of kinetics involved, and other mechanistic requirements and implications were discussed. As this was an introduction to both concepts in organic chemistry and a new teaching style, it was essential to provide guidelines for efficient and profitable group discussion. After this brief description, the remainder of the class time was spent within these group settings. Those involved in subgroup 1 were given one 30 × 20-inch poster board and two color markers per group. Group 2 was given molecular model kits (Styrofoam balls and toothpicks can also be used). Name tags on string necklaces were given to those in group 3. The names on the tags were Nucleophile, Central Carbon, Leaving Group, and two Side Chains. Questions that guided the students were placed on an overhead projector slide. These five queries (one overhead) were vital to the success of the exercise, as they covered the basics of the mechanisms (questioning the point of the mechanism where the leaving group leaves and when the
Figure 1. Flowchart depicting the partitioning of the large class into small groups. This method of dividing the class can easily be tailored to suit the specific class size by altering the number of initial main groups (i.e., A, B, C).
Journal of Chemical Education • Vol. 76 No. 1 January 1999 • JChemEd.chem.wisc.edu
In the Classroom
nucleophile attacks, and a description of the intermediate or transition state). Since the students had a goal to attain, their discussion was purposeful. The students in group 1 had to answer the queries on their poster boards in note form or with other written words. This type of learning addresses the learning style of students who prefer to read and see ideas on paper. Those in group 2 investigated the assigned mechanism using conceptual visualization. Using model kits, they were able to see the manner in which the nucleophile attacks the carbon center and at which point the leaving group leaves the central carbon atom. Learners in group 3 were presented with a more abstract process, role playing. This activity ideally suits the learner who benefits from participating in problemsolving exercises. At this point, the students were focused on only one type of mechanism, which was given to them on their original assignment sheet. Groups completed their work in about 6–10 minutes. In all cases, group members understood the ideas derived from the guiding questions. At this point, each group was asked to share its answers with an assembly of students who had completed the exercise for the alternate reaction and had answered the questions using a different learning activity. For example, those in major group A, subgroup SN1-1 (poster boards) could meet with group A, subgroup SN2-2 (molecular models). In this way, all students were exposed to two different forms of learning as well as to the alternate mechanism. A further 10 minutes were allotted to this sharing of the presentations. Upon completion of the “share” stage of the class, students were encouraged to dissipate into pairs or trios that included students who had already covered both S N1 and SN2. Higher-order questions that encouraged thinking beyond the basics were posed on a series of overhead slides (3–4 questions in a 50-minute class). For instance, one question showed the structures of methyl bromide and tert-butyl bromide and asked about the nature of the mechanism. We found that students prefer to have a guiding hint (e.g., stability of the transition state or intermediate) listed on the slide. After some discussion, students voted on the answer to the posed question by a show of hands. This helped to provide some immediate feedback on the success of learner comprehension. The answers were then explained in further detail by the instructor. At the end of the question period, a comparative table relating all the key concepts involved in understanding SN1 and SN2 mechanisms was distributed and discussed. This was used as a summary and conclusion of the learning episode and was also a valuable study resource for future classes and exams. Student Evaluation Just before the end of the class, evaluation surveys were distributed because we feel that the learners themselves should judge the success of an educational strategy. Students were asked to evaluate how much they learned compared to what they would learn in an ordinary 50-minute lecture on a scale of 1 to 10, where 5 is the amount of an ordinary lecture.
More than 98% of the students stated that they learned a substantial amount more than they would have learned in a regular lecture format. Many of them responded that in the future, they would like to have more opportunity to learn in this type of environment. As an additional evaluation of the success of the teaching episode, an unannounced quiz was conducted the following week. The students were asked to write down the two key mechanisms covered in the previous lecture as well as a few key words for each reaction pathway. More than 85% of respondents demonstrated good comprehension of the important points from the previous class, even though there was no warning of the quiz. In this manner, we have shown that the responses indicate a high level of student recall, when compared with levels achieved by a traditional lecture style (8). Conclusions It is often believed that large classes are most effectively taught via a traditional lecture format. However, it has been shown that with planning, group discussion and active learning can be incorporated into the large classroom. Student evaluations demonstrated that the students themselves not only enjoyed the class, but also felt that they learned more. Collaborative learning processes can be used in the classroom at any level to enable chemistry students to improve their understanding of key concepts. By paying careful attention to different learning styles in the design of the teaching episode, the requirements of a variety of learners can be addressed. Acknowledgments We would like to thank Andy Farquharson and Barbara Judson of The Learning and Teaching Centre at the University of Victoria for motivation. We appreciate many fruitful discussions with Cornelia Bohne and David Berry. We are also grateful to Fred Fischer for supplying us with valuable class time to initiate these new ideas. We thank the Natural Science and Engineering Research Council of Canada (NSERC), the University of Victoria, and the Department of Chemistry for financial support. Literature Cited 1. Meyers, C.; Jones, T. Promoting Active Learning; Jossey-Bass: San Francisco, 1993. 2. Davis, B. Tools for Teaching; Jossey-Bass: San Francisco, 1993. 3. Brookfield, S. The Skillful Teacher; Jossey-Bass: San Francisco, 1990. 4. Kogut, L. S. J. Chem. Educ. 1997, 74, 720. 5. Felder, R. M. J. Chem. Educ. 1996, 73, 832–836. 6. Ross, M. R.; Fulton, R. B. J. Chem. Educ. 1994, 71, 141–143. 7. Experiences in Cooperative Learning: A Collection for Chemistry Teachers; Nurrenbern, S. C., Ed.; Institute for Chemical Education: Madison, WI, 1995. 8. Ostercamp, D. L. J. Chem. Educ. 1992, 69, 318.
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