In the Classroom
Teaching Introductory Organic Chemistry: A Problem-Solving and Collaborative-Learning Approach Lois M. Browne Department of Chemistry, University of Alberta, Edmonton, AB, T6G 2G2, Canada Edward V. Blackburn Faculté Saint-Jean, University of Alberta, Edmonton, AB, T6C 4G9, Canada
Over the past quarter century, chemistry departments, faculty, and students have been challenged to change their approach to the study of chemistry (1–3). The need for a laboratory-centered curriculum (4) in which critical, creative, and complex thinking skills are developed has been well articulated (5–8). During the past decade, the laboratory component of introductory organic chemistry courses has received justifiable criticism. As Pickering remarked (9), It is the process of abstraction that is so badly ignored. Organic labs have degenerated into cooking.…What matters for [students] is not practice of the finger skills of organic chemistry, but practice in the style of thinking of organic chemists.
The introduction of unknowns in lab experiments, not only at the University of Alberta but at many other colleges and universities (10, 11), was in response to student and faculty condemnation of the cookbook approach to teaching the organic chemistry lab. In spite of this, course exit questionnaires have continued to demonstrate student dissatisfaction with the experience in introductory organic chemistry. Common complaints are that students perceive little correlation between laboratory and lecture components; and therefore they cannot see the relevance of the laboratory curriculum. During our attempt to address these concerns and to improve our students’ learning experience, we were made aware1 of the way of learning espoused by Wilson (3, 12). We decided to investigate the possibility of adapting the methodology he developed for small classes to accommodate the 250+ student course sections at the University of Alberta. The results of this study are presented in this paper. Introductory organic chemistry at the University of Alberta is taught either in the freshman (CHEM 161/163) or sophomore (CHEM 261/263) year2 of the student’s program (13). The course is available to all students during the twosemester Fall/Winter Session or during the intensive six-week Spring Session,3 the language of instruction being English or French.4 The Problem-Solving Thesis and Concept of Collaborative Learning Instructor and laboratory coordinator collaborated to create an integrated, lab-centered experience in which students were introduced to organic chemistry from a problem-solving perspective in an attempt to develop the problem-solving and practical skills that are fundamental to this experimental science. To foster the critical, creative, and complex thinking skills of 1104
our students, we decided to develop a collaborative learning environment (14–23) in which students solve experimentbased problems in groups. The hope was to develop study groups that would help and encourage students, new to university life, as they studied organic chemistry, and also allay the evident apprehension5 of many of the students. Problemsolving groups of four to eight students were therefore formed6 with the purpose of solving challenging, instructorprovided problems—problems not exercises (PNE) (3), which emphasize the experimental nature of chemistry—and to planning the problem-solving labs (PSL) (12). The Lecture Component Whenever possible, the course instructor presented topics from a practical problem-solving perspective. In an attempt to model the thought processes of the organic chemist, experimental results were discussed, explanations proposed, and tests of hypotheses developed. This process was introduced, for example, through a study of the free radical halogenation reactions of alkanes. After a review of the experimental evidence, a mechanism was developed. This was followed by a discussion about how this mechanism might be tested and what predictions might be made on the basis of the mechanism. This thought process model was developed further during the study of nucleophilic substitution and elimination reactions. As the course progressed, students were more and more able to actively participate in the thought process; there was a gradual development of critical and creative thinking. The instructor ensured correlation between lab and lecture by relating the problem to be solved in the lab to the current lecture material. For example, criteria of purity were discussed at the start of the course, thereby introducing students to the concepts of melting point, mixed melting point, boiling point, refractive index, thin-layer chromatography, and infrared spectroscopy before their first PSL. The first PSL presented the problem of assessing the purity of a solid unknown and then identifying it. The problem-solving nature of chemistry and the collaborative learning process were reinforced through the PNEs.7 Library skills were developed and emphasized as students were shown that chemists situate their own work in the continuity of scientific thought that has elaborated over the years. The first PNE, therefore, consisted of a literature search in which students made extensive use of Chemical Abstracts and Science Citation Index. Subsequent PNEs emphasized the experimental nature of chemistry and paralleled the methodology reported by Wilson (3). Experimental data were taken
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In the Classroom
from the literature. Students were queried about techniques used and were often required to postulate a mechanism. The Lab Component The greatest fundamental change resulting from our work was in this component. At the University of Alberta, teaching assistants (TAs) under the supervision of the laboratory coordinator teach approximately 50 scheduled lab sections per week (maximum 22 students per class). Generally, the TAs have the responsibility to introduce the experiment, explain underlying experimental concepts, teach techniques, monitor the students’ progress, and evaluate their performance. The large number of students involved imposed constraints on the adaptation of our laboratory course to a problemsolving curriculum. Students could not have free access to labs; they needed to adhere to scheduled lab periods.8 However, to implement the problem-solving curriculum, students needed access to technical information, and this was provided primarily through a custom-designed lab manual (24 ) and videotaped demonstrations of techniques (25, 26 ). The topics of the traditional “cookbook” laboratory course were maintained in the PSL course so that students’ learning and performance in the problem-solving course could be compared with that of students in the traditional course. The first semester experiments introduce the student to basic organic chemistry technical manipulations (see Table 1 for a summary). A practical problem is posed that requires the use of a specific technique to work out the solution. For example, rather than studying melting point measurements, recrystallization, and thin-layer chromatography as a focus, the student develops these techniques in order to solve the practical problem of determining the purity of and purifying and identifying an unknown solid. Each new PSL introduces a new technical skill while repeating the use of those learned earlier. To facilitate problem solving, the custom-designed student lab manual used a guided-inquiry approach. Each PSL was divided into experimental tasks. A list of available chemicals and apparatus was provided, along with pertinent factual information and “hints” to assist the student in developing an experimental strategy to complete a specific experimental task.
A series of questions was included as a prelab assignment; the questions “walk” the students through a possible solution to the problem,9 thereby helping them understand what was required in the experiment. At the beginning of each laboratory class, the TA gave a brief review of the day’s experimental task, demonstrating a possible approach to solving the experimental tasks by “thinking aloud” in order to display the thought process for the student to mimic. The basic techniques were described in the lab manual and the showing of in-houseproduced videos (25, 26 ) of each technique as it was encountered emphasized the correct manipulations. Following the TA review and videos, the groups worked out their own plans of action. After TA approval of the plan, the groups separated into pairs of students and proceeded to implement the solution to the problem. Students soon developed confidence in their own problem-solving capabilities. This allowed a transition from group planning and partner work to individual experimentation as the semester progressed. Implementation The problem-solving approach was used during four successive academic sessions. After the completion of each course sequence, the curriculum was reviewed and refined. The new pedagogy was first implemented in Spring Session 1995, a class of 100+ freshman and sophomore students, and the lab-centered curriculum was an immediate success. However the PNEs were less well received. They were too numerous (seven during a three-week period) and were found to be very difficult. It was therefore decided to reduce their number and remove some of the more taxing problems. In Fall Session 1995, the course was taught to approximately 250 freshman students. The problem-solving strategy was again a success, with a majority of students acknowledging its effectiveness: I really enjoy the problem-solving techniques used in this class. It makes concepts more clear and understanding easier.
In the problem-solving labs, TAs need to be interactive in their instruction. Resources were therefore developed to help new TAs in leading interactive discussion sessions with
Table 1. Techniques and Concepts Taught as Problem-Solving Laboratories Technique
Experimental Topic
Handling chemicals safely: weighing and measuring Melting point measurements Mixed melting point measurements
Melting point measurement and thermometer calibration (group plan and partner work)
Thin layer chromatography Recrystallization (single solvent, mixed solvent) Filtration (gravity, hot gravity, vacuum)
Assessment of purity; purification and identification of a solid (2 lab classes)
Interpretation of infrared spectra
Review and identification of functional groups
Simple distillation Boiling point measurement
Separation and identification of a compound in a solution
Liquid–liquid extraction Chemically active extraction Drying liquids (drying agents) Sublimation
Separation of a mixture of acidic, basic and neutral compounds (2 lab classes)
Solid–liquid extraction Heating under reflux
Isolation of trimyristin (individual work begins)
Reactions under reflux using anhydrous conditions Removal of noxious gases generated during a reaction
The Diels–Alder reaction
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In the Classroom
their students. Four concurrent laboratory sessions were audiotaped. The student questions and style of speech were analyzed. A list of student questions was compiled for each PSL and used to develop the script for an animated videotaped demonstration10 of effective interactive teaching. All freshman organic chemistry students (~1000) took the problem-solving laboratory component in Fall Session 1996. One-third of the TAs assigned to the course had not previously instructed introductory organic chemistry. In contrast, the sophomore class was taught using the traditional lab methodology. Again the problem-solving course was very successful. The improvement in student performance in the problem-solving laboratory compared to the traditional laboratory was assessed through the lab exam. Students in the problem-solving course performed ~6% better on similar lab exams. They were also more successful than their sophomore compatriots in answering questions about how and why to carry out a basic technique. Evaluation Students’ experience of both the problem-solving course and the traditional course was surveyed through anonymous course-exit questionnaires. Statements were made and the students were asked to rate their agreement or disagreement with the statement using the scale 5 = strongly agree to 1 = strongly disagree. Student response to the statement “Overall, the lab is a valuable part of the organic chemistry course” was consistently higher for the problem-solving lab course (3.8–4.1) than for the traditional lab course (3.2–3.5). An attempt was made to determine specific aspects of the lab program that influenced the students’ perception of the course. Generally students were aware of the importance of technical skills and evaluated videotaped demonstrations favorably. As previously mentioned, students frequently are frustrated because they do not understand the correlation between the lecture and the practical chemistry that they carry out in the laboratory. However, students involved in the problem-solving approach to organic chemistry grasped the interrelationship of lecture and lab, especially during the Spring Session when the course sequence is learned in a concentrated time period. Some students questioned the value of collaborative learning for the PSLs and PNEs in the Fall Session, possibly because group members did not have well-defined tasks. As a result, not all members of the group contributed equally. In contrast, students perceived that they learn more readily and embrace problem solving more readily when working with partners. In the Spring Session the groups are more cohesive and the intensity of learning is far greater. The smaller student numbers (100–120) during the spring allow students to choose their groups, a process that is impossible in the fall. Klemm has reported (14 ) that “students need to believe that they are linked with others in a way that ensures that they all succeed together. Each participant may have a different role, but that role must be crucial to the group process.” The importance of group participation and the role of each member will be emphasized as we further refine this pedagogical approach to learning. An objective of the problem-solving lab course is to build student confidence and independence in experimental work.
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To evaluate this, students were asked to give their impression of the first term problem-solving laboratory course. The survey showed that students learning laboratory skills in organic chemistry using the problem-solving approach have a stronger belief in their capabilities to carry out basic practical chemistry; they also are more confident about their knowledge and understanding of the underlying concepts than students learning laboratory skills using the traditional, recipe-style approach. Student demands on TAs changed as a result of the new approach. The TA instruction became focused on helping students to be successful through hints, rather than step-bystep explanations. Most TAs agree with the course format and believe that this approach benefits student learning, as reflected in the following comment: I enjoyed teaching the problem-solving labs in the first term. The difference between this course and the traditional one could be noticed right away. Here, students are given all the tools to do the experiment instead of simply the written procedure. They are required to think, understand all principles, then experiment and make decisions (with minimal assistance from the TA). Because it is more challenging for them than to blindly follow the procedure, they get involved much more and they do enjoy it a lot more. All experiments seem to be more rewarding for students later when they worked on their own. Students question each step they need to do, so they develop much more understanding of what’s going on. The techniques and the basics of organic chemistry that they learn, they remember longer and know how to apply them in following experimental organic chemistry courses. This was obvious at the beginning of the second semester course, when the class was a mixture of students trained by problem-solving and in the traditional way. Overall, I hope that I can teach the problemsolving course in the Fall of 1996.
Conclusion We have shown that a collaborative learning and problemsolving approach to teaching introductory organic chemistry is successful with large multi-section classes.11 We are continuing to refine the method. WWW material is being developed as an additional teaching resource for PSLs and will be available to students during Spring Session 1998. The importance and responsibilities of each study group member must be emphasized and groups encouraged to develop role descriptions for each member. Notes 1. We thank Shirley Ann Wacowich for sharing her learning experiences with us. 2. CHEM 261/263 requires a prerequisite course in general chemistry. 3. In the Spring Session, the course is taught to a combined group of freshman and sophomore students. 4. EVB was the instructor for both English and French language problem-solving lecture sections. 5. This apprehension appears to be the result of comments from physicians, dentists and other nonchemist professionals who completed organic chemistry prerequisites more than a decade previously! 6. Groups were created in the first laboratory session. 7. There were five PNEs in each one-semester course. Each group submitted one set of answers for each PNE and points were awarded for scores above 70%. 8. Each course requires 3 hours per week, 11 weeks per term, of
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In the Classroom lab work. 9. A typical problem-solving laboratory exercise from the student laboratory manual and student report book is appended. A copy available upon request. 10. An animated videotape entitled Melting Point Determinations: FAQs (produced by LMB in 1996) shows effective interactive teaching by a TA. This is used in our TA training program. 11. Our methodology has also been embraced at other Western Canadian institutions, in particular, Okanagan University College.
Literature Cited 1. Venkatachelam, C.; Rudolph, R. W. J. Chem. Educ. 1974, 51, 479–482. 2. Kalsai, P. S. J. Chem. Educ. 1976, 53, 553. 3. Wilson, H. J. Chem. Educ. 1986, 63, 484. 4. Moore, J. W. J. Chem. Educ. 1989, 66, 15–19. 5. Pickering, M. J. Chem. Educ. 1985, 62, 874–875. 6. Barrow, G. M. J. Chem. Educ. 1991, 68, 449–453. 7. E¯ge, S. N., Coppola, B. P.; Lawton, R. G. J. Chem. Educ. 1997, 74, 74-83. 8. Coppola, B. P., E¯ge, S. N.; Lawton, R. G. J. Chem. Educ. 1997, 74, 84–94. 9. Pickering, M. J. Chem. Educ. 1988, 65, 143–144. 10. Cooley, J. H. J. Chem. Educ. 1991, 68, 503–504. 11. Sowa, J. R. J. Chem. Educ. 1989, 66, 938–939. 12. Wilson, H. J. Chem. Educ. 1987, 64, 895–896. 13. University of Alberta Calendar; Office of the Registrar and Student Awards, University of Alberta, Edmonton, Alberta, Canada T6C 2M7. 14. Klemm, W. R. J. Vet. Med. Educ. 1994, 21(1), 2–6.
15. Gabbert, B.; Johnson, D. W.; Johnson, R. J. Psychol. 1986, 120, 265–278. 16. Johnson, D. W.; Johnson, R. T. J. Educ. Psychol. 1981, 73, 454– 459. 17. Johnson, D. W.; Skon, L.; Johnson, R. T. Am. Educ. Res. J. 1980, 17, 83–94. 18. Johnson, D. W.; Johnson, R. T. Cooperative Learning and College Teaching 1993, 3(2). 19. Light, R. J. The Harvard Assessment Seminars, 1990; Harvard University: Cambridge, MA, 1990. 20. Cooper, M. J. Chem. Educ. 1995, 72, 162–164. 21. Doughert, R. C.; Bowen, C. W.; Berger, T.; Rees, W.; Mellon, E. K.; Pulliam E. J. Chem. Educ. 1995, 72, 793–797. 22. Wright, J. C. J. Chem Educ. 1996, 73, 827–832. 23. Felder, R. M. J. Chem Educ. 1996, 73, 832–836. 24. Browne, L. M. Organic Chemistry Experiments. Chemistry 161/163, 1998–1999 edition. This manual is available at nominal cost from the University of Alberta Bookstore. 25. Browne, L. M.; Auclair, K. J. Chem Educ. 1998, 75, 383–384. Browne, L. M.; Auclair, K. Techniques in Organic Chemistry, Part 1 and French translation, Techniques en Chimie Organique, Part 1; J. Chem. Educ. Software 1998, SP20; topics are handling chemicals safely, filtration, recrystallization: the single solvent method, recrystallization: the mixed solvent method, and thin layer chromatography. 26. Browne, L. M.; Auclair, K. J. Chem Educ. 1998, 75, 1055. Browne, L. M.; Auclair, K. Techniques in Organic Chemistry, Part 2 and French translation, Techniques en Chimie Organique, Part 2; J. Chem. Educ. Software 1998, SP22; topics are reflux, using a separatory funnel, simple distillation, distillation at reduced pressure, and using a rotary evaporator.
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