In the Classroom
A Poster Session in Organic Chemistry That Markedly Enhanced Student Learning P. A. Huddle Department of Chemistry, University of Witwatersrand, P O Wits, 2050, South Africa;
[email protected] Teaching of ChemII Organic at Wits Students at the University of the Witwatersrand (Wits) take a general course (ChemI) in their first year of study of chemistry. At both the major and auxiliary levels this general course includes a small section of organic chemistry covering the various functional groups and the general physical and chemical properties of organic compounds. In their second year of study, these students take ChemII, a chemistry course involving four modules of 24 lectures each: Analytical II, Inorganic II, Organic II, and Physical II. For the last 12 years, the 24 lecture periods of the Organic II module have not been used solely for information delivery. Rather, this module has consisted of a combination of 14 overview lectures on various aspects of the course coupled with 10 small group tutorials. In this format there has been a marked shift in emphasis from lecturing to student-directed learning in an attempt to get the students actively involved in and responsible for their own learning of organic chemistry (4–6 ). Student manuals have been produced for the module, which contain all the learning goals and a summary of important facts for each section together with carefully selected problems to illustrate the learning goals. References to current textbooks are given for most learning goals and problems. To give structure to the module, all the reactions are clustered into the five classes of organic compounds (7, 8): (i) saturated hydrocarbons (alkanes), (ii) unsaturated hydrocarbons (alkenes, alkynes), (iii) saturated heteroatom compounds (alcohols, alkyl halides, etc.), (iv) unsaturated heteroatom compounds (aldehydes, ketones), and finally, (v) composites of iii and iv (esters, amides, etc.). Each class of compound is addressed separately, focusing on the characteristic reaction patterns (9) involved (substitution, addition, or elimination), the conditions that favor each pattern and related aspects of reactivity (e.g., regioselectivity or stereoselectivity of reactions; presence of inductive or mesomeric effects). Students are encouraged to approach each problem by asking, “what class of organic compound is this?”, “what kind of reaction can I expect it to undergo?”, “are there any specific aspects to the reactivity of the compound that I need to bear in mind when deciding on the product(s) of the reaction?” 1154
Over the years, we took heed of the advice of Moore (10) and Black (11) in attempts to encourage more active involvement in this Organic II module by the students in both lectures and tutorials. The introduction in 1995 of 5-minute minitests at the end of every alternate tutorial session resulted in increased student participation in these small group sessions, forced most students to keep up to date, and boosted the organic pass rate relative to the other ChemII modules for that year (see Fig. 1). Despite this, the pass rate for the Organic II module decreased alarmingly in 1996 and 1997. Even the mini-tests were insufficient to encourage more than 40% of students in 1996 and 30% in 1997 to pass the final Organic II examination. If these trends continued, we were looking at ~20% of students passing Organic II in 1998. Table 1 shows the steady decline in the number of students registering for ChemII (major) at Wits from 1993 to 1998 and a decrease in the Organic II examination average from 56% in 1993 to 41% in 1997. A decline of about 10% in the Table 1. Achievements of ChemII (Major) Students in Various Modules, 1993–1998 Year a
Item
1993 1994 1995 1996 1997 1998
Number of students
94
75
74
57
43
37
Highest mark in ChemII
83
85
81
88
90
68
Exam average, Organic
56
54
58
43
41
50
Exam average, Inorganic
60
61
55
61
52
39
Exam average, Physical
54
55
54
50
45
36
Exam average, Analytical
57
54
50
61
51
39
Overall pass ChemII b (%)
80
72
80
75
69
50
aThrough
1995, inorganic and analytical chemistry were presented in the first semester, and organic and physical chemistry in the second. Beginning in 1996, inorganic and physical were presented in the first semester; analytical and organic, in the second. bStudents can pass ChemII if they achieve an overall 50% average, but they must achieve at least 40% for each module.
90
Analytical 80
Inorganic Physical
70
% Students Passing
Regularly, journal articles inform us of the steady decline in the number of students interested in pursuing a chemistry major along with an increase in the number who drop out along the way. Students come to college less prepared than a decade ago and appear more intent on boosting their grade point average than on learning (1). The number of students who are successful in chemistry courses is also decreasing steadily (2). Students seem to have both weak motivation and minimal self-discipline, and thus are becoming more dependent on lecturers to “make them learn” (2). “They want the nittygritty work done for them” (3). We have found the introduction of a poster session into our Organic II module to be a useful strategy for combating these trends.
Organic
60 50 40 30 20 10 0 1993
1994
1995
1996
1997
1998
Year
Figure 1. Percentage of students passing the examination in each ChemII module from 1993 to 1998.
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In the Classroom
examination average for the other ChemII course modules (inorganic, physical, and analytical) during that period is also evident. The combination of the four modules in ChemII for the first and second semesters was rearranged in 1996 from an inorganic/analytical–organic/physical combination to inorganic/physical in the first semester and organic/analytical in the second semester. This led to an improvement in the marks of the (perceived as easier) modules of inorganic and analytical chemistry in each semester in 1996 at the expense of the physical and organic modules (see Fig. 1). Despite this rearrangement, the examination average and percentage pass for the inorganic and analytical modules in 1997 and 1998 dropped considerably along with the physical chemistry marks. Note, however, the increase in the Organic II pass rate for 1998 after the introduction of the poster session. Pass rates in chemistry in American universities have also been dropping steadily. Katz ascribes the decline in student numbers in chemistry and the decreasing success in examinations to an increase in the number of students being in a “futile cycle” where negative emotional responses to learning activities drain the students of energy, decrease useful output, and lead to last-minute cramming and rote learning (2). Organic chemistry, especially, is a dreaded “washout” course that “has a bad reputation of mythic proportions” (2). Katz believes that it is vital to develop student independence and responsibility, and that lecturers must adopt strategies that get students involved in a course to the extent that they shift into a “productive cycle” where they experience positive emotions toward a course, resulting in productive learning and deep conceptual understanding. Our students, like their American counterparts, probably have similar negative feelings toward organic chemistry—it is not a subject that can be crammed the night before a test or examination. Rote learning alone is insufficient to pass Organic II; it requires comprehension and constant practice of problems. Each year of study builds on the preceding year. Failure to grasp organic concepts taught in the ChemI course hampers understanding of the Organic II chemistry module, which, in turn, causes the Organic III module (with its retrosynthesis component) to become a nightmare and an insurmountable hurdle to a degree in chemistry. We concede that many of our students are in futile learning cycles where they never seem to put in the “activation energy” required of them to come to grips with a subject (the quip around the university at present is “the students want a degree, not an education.”) In 1998, for the first time in the last 30 years for which records are still available in this department, no ChemII student achieved above 70% for the course and there was debate as to whether the prestigious award for the top ChemII student should be granted. To determine whether there was any change in the composition of the ChemII class in 1998 relative to previous years, an analysis of the ChemII classes from 1993 to 1998 was undertaken (see Table 2). This revealed that the average mark attained for the Chemistry I course by Wits students present in the ChemII class has remained fairly constant at around 63% from 1993 to 1998. The only marked change in the class has been in the increasing percentage (from 7% to 22%) of students who attained a credit for ChemI from another tertiary institution in South Africa and were then accepted into the ChemII course by Wits. Research by a postgraduate student in our department has shown that students
Table 2. Profile of ChemII Students, 1993–1998 Year
Item
1993 1994 1995 1996 1997 1998
Number of students
95
76
79
57
48
41
Ave. ChemI mark (%), Wits students 61.3 63.6 64.0 64.7 62.5 62.6 % major students from ChemI, Wits
65
59
58
58
74
58
% aux students from ChemI, Wits
28
33
33
33
13
20
7
8
9
9
13
22
19
23
19
17
% students from other 3° institutionsa % students repeating the course
19 3 [sic!]
aOther tertiary institutions include the historically black universities (HBUs) in South Africa; the University of South Africa, UNISA (degree by correspondence); and technikons and teacher training colleges.
from these other tertiary institutions are rarely successful in their first attempt at our ChemII course. This intake of less well prepared students exacerbated the problems of weak motivation and poor self-discipline of our students. The standard of the ChemII course at Wits has not been compromised to accommodate poorly motivated or weaker students; all students still need to understand and be able to apply the same concepts as 10 years ago if they wish to pass the course. We do not grade students on a curve. All examinations go to an external examiner who ratifies the standard relative to previous years. In other words, the quality of entering students may alter but the exit criteria from our ChemII course remain unchanged. At the end of the first semester of 1998 we were informed that the ChemII class had achieved a mere 23% pass in Inorganic II and 15% in Physical Chemistry II, down from an average of about 70% five years ago. There seemed to be a general apathy in the class, with no outstanding student leading the way and encouraging healthy competition among the other students. Mediocrity ruled. Lecturers were asked to come forward with suggestions on how to improve on the results in the second semester. The Intervention Heedful of the advice of Katz (2), I realized that I had to try some new way to get students involved in Organic II in such a way that they entered a productive cycle of learning. It was too late to change the organic module further to total student-directed learning; this would require considerable reorganization of material by the course lecturers. So, instead, I adopted poster presentations as a means of getting students more involved in the course and forcing a deeper level of understanding of concepts. The idea of using posters came from the article by Sisak (12), who pointed out that it is only when one is totally responsible for presenting something that one takes responsibility for one’s learning and prepares adequately. Also, Clouston and Kleinman found that retention of information can increase to 90% when students become active participants in their learning environment (4). They found that teaching others is the most effective way to learn something. Choice of the topic for the posters now became an issue. What should the posters be about? Several possibilities came to mind. The final choice of topic was found to be crucial to the success of this innovation and arose from the following factors: One of the organic learning goals in our ChemI course involves “identifying nucleophilic and electrophilic sites in molecules and showing how the concept of interac-
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In the Classroom tion between such sites can provide a guide to the correlation and prediction of many organic reactions”. Yearly, the poor attempt by ChemI students to answer questions on this learning goal in their final examination was proof that they did not understand the concept beyond the superficial level of rote learning of the definitions of nucleophile and electrophile. Few students could apply the concept to a new situation. Discussions with students in second-year organic tutorials over the last ten years had highlighted the astonishing fact that many students could not identify which of two atoms in a covalent bond was the more electronegative! Obviously, this was a major stumbling block to being able to identify nucleophilic and electrophilic sites in organic molecules and then predict a reaction pathway. A chance remark I overheard made by the top student one year when he failed his second Organic II mini-test: “I am going to have to come to terms with these silly little arrows if I want to pass this course!”
These three factors had sensitized me to the fact that curly arrows and the rules around them are fundamental to organic chemistry. Many pathways are easily remembered if one understands how to draw the arrows; the products of many reactions can be predicted if one can identify the nucleophilic and electrophilic centers in the reacting molecules. How many students in ChemII were capable of this? Could a poster presentation on these arrows force students to come to an understanding of one of the most basic concepts in organic chemistry and hence increase their interest in this topic? We would never know unless we tried. The midyear results of the ChemII students were so poor that the course supervisor was prepared to try anything. The following 3-hour poster session was planned: You will prepare an organic poster to be presented by you during the last week of organic practicals. Marks will be awarded for the accuracy of the organic chemistry as well as for layout, accuracy, originality, neatness, and ease of reading from afar. The poster will be on the use of curly arrows in organic chemistry to show the movement of electrons during the course of a reaction. You will assume that you have just devised this technique and wish to present it to the scientific world (the other students in Chem. II, the organic staff, and postgraduate students) at a conference (the last organic II laboratory session). The poster should consist of six A4 sheets of paper pasted onto a colored sheet of cardboard. On the first A4 sheet you must explain the rules for the use of curly arrows (in your own words!) Use the other five A4 sheets of paper for each of the five classes of organic compounds. On each sheet, give the class of organic compound (e.g., unsaturated hydrocarbons), the characteristic reaction pattern that the compound undergoes (electrophilic addition), and then a problem from any organic textbook involving that class of compound. Outline the solution to the problem using curly arrows. Cite the references to the source of all your problems. ( Do not use problems from past examination papers, your lecture notes or laboratory manual). On the afternoon of the presentations, I organized for all the organic chemistry staff and postgraduates to be available in the laboratory. Below is an example of how a presentation proceeded. The purpose of elaborating on a presentation is to demonstrate how many different concepts need to be under1156
stood by students before they can draw the arrows. An experienced chemist draws them almost without thinking, oblivious of all the underlying knowledge required. LECTURER: I see you have a new idea to explain the mechanism of organic reactions. STUDENT: Yes, you can use arrows to show the movement of electrons during a reaction. LECTURER: How do I know where to draw the arrows? STUDENT: The arrows are always drawn from the nucleophile—the electron-rich center—to the electrophile—an electron-deficient center. LECTURER: How do I decide which is the nucleophile and which the electrophile? STUDENT: It is dependent on the electronegativities of the various atoms. For example, in the C–O bond, oxygen is more electronegative than carbon, so the oxygen atom will be the nucleophile and the carbon the electrophile. LECTURER: You use two kinds of arrows—how will I know which arrow to use? STUDENT: A single-headed arrow shows the movement of one electron (a radical); the double-headed arrow is used when two electrons move during the reaction. LECTURER: How do I know whether one or two electrons are moving in a reaction? STUDENT: If bonds break homolytically to produce radicals, single-headed arrows are used; if a bond breaks heterolytically to produce a cation and an anion, a doubleheaded arrow is used. LECTURER: What do these terms “homolytic” and “heterolytic” mean? How do I decide whether a bond will break “homolytically” or “heterolytically”? STUDENT: “Homolytically” means the bond breaks so that each atom involved in the bond receives one electron; this occurs when both atoms have the same or similar electronegativity. “Heterolytic” bonds cleave so that the more electronegative atom receives both the electrons.
This could lead to further discussion of how they determined which atom in a bond is more electronegative, further examples of electron-rich and electron-poor centers in organic molecules, and finally, an illustration of the use of the two types of arrows in the problems they had chosen. On a few occasions, after a presentation, a lecturer or postgraduate student spent some time helping a student clarify one or more concepts that apparently had not been mastered fully in preparation of the poster. The Results One student (NJ), who was repeating the module for the second time (i.e., her third year in ChemII Organic), met me at her poster with shining eyes, “All the organic chemistry just fell into place when I prepared this poster. I never realized it was so-o-o easy.” She obtained 29% for ChemII Organic in 1996, 41% in 1997, and 71% in 1998. Another student said triumphantly, “I could understand where all the arrows were going in your lecture today!” Big Deal! “Today’s lecture” was the ninth of the 14 overview lectures and the explanation of the use of curly arrows had been covered in lecture one.
Journal of Chemical Education • Vol. 77 No. 9 September 2000 • JChemEd.chem.wisc.edu
In the Classroom
Some of the more reserved students, who seldom asked questions in lectures or tutorials, explained the concepts extremely well and stated that the effort required of them to prepare their posters had been more than compensated for by their increased understanding of organic chemistry. Many students thanked me for organizing the poster session even though they admitted that they had been very nervous for their presentations. There were five students who made no effort for their posters. Their presentations were extremely poor. Three of these students, after listening to the presentations of other students, asked for a second chance to prepare and present their posters. This was agreed upon with the maximum possible mark for a rerun pegged at 66%. Within the next two weeks all three students adequately prepared and presented their new posters. The other two students made no further effort and went on to fail the Organic II module and the ChemII course. Students were forced to come to an understanding of many basic concepts before they could adequately prepare their posters and presentations. This understanding of how to determine nucleophilic and electrophilic sites in organic molecules, and hence an ability to predict the pathways of reactions they had not encountered before, was highly motivating for the students. It shifted them from the futile emotional domain into a productive one, where they now believed they could pass the Organic II module. The positive emotions generated towards organic chemistry once the students had acquired an understanding of the basic concepts provided them with the energy to complete further tasks required to pass the module. In the cooperative small group organic tutorial sessions that followed the poster presentations, attendance and active participation increased markedly, interest in the course heightened, and answers to the test and examination questions were of a much higher standard than in previous years. Several students told me that they now felt organic chemistry was a manageable course, whereas before they prepared their posters, it had been a jumble of reactions—many of which they had copied incorrectly into their notes from the board, as they had not understood them at all. It took approximately 5 minutes per student to present a poster. It would have taken at least 3 hours for one person to oversee 35 students. Thus, help from other members of staff was essential. Also, each student had the benefit of giving several presentations. As a result, they could improve on their initial rather nervous presentation and reinforce their understanding of concepts. Furthermore, since marks were awarded by several examiners, the possibility of favoritism was eliminated. Next year, presentations will not be limited to organic personnel. All interested staff and postgraduates will be invited to attend and two afternoons will be allocated exclusively for poster presentations. This ChemII class of 1998 performed poorly in the Analytical II, Inorganic II, and Physical Chemistry II modules, where overall pass rates decreased by 30% (see Fig. 1). Predictions for the pass rate in the Organic II module were around 10%, but the final pass rate was 52%. Table 1 reveals that the average mark for the final Organic II examination was up by 10% from the previous year for a class whose average examination results in the other three Chem. II modules had decreased by 10%. The standard of the final Organic
II paper was comparable to that in previous years. In fact, the external examiner (GCG) commented that the paper was “more challenging” than in previous years yet the “quality of the answers was far superior”. The improved examination results and percentage pass in the ChemII Organic module in 1998 relative to 1996 and 1997 must be due in some measure to the increased understanding of and resulting commitment to this topic by the students following the poster session. Conclusion Over the years I, together with a colleague, have kept abreast of the literature and introduced various techniques into the Organic II module in an attempt to increase student participation and achievement in the module by— •
a shift in emphasis from teaching to learning (4);
•
introduction of small group cooperative tutorials (5, 6);
•
involvement of students in lectures (11);
•
a dry laboratory on stereochemistry involving ball-andstick and Allyn and Bacon space-filling models;
•
introduction of mini-tests, etc.
Never have I been so upbeat about the effect of a change as I have been after the introduction of the poster session. Colleagues in the department commented on the improved attitude of the students to the ChemII Organic module. The organic staff is now waiting to see how these students perform in the ChemIII Organic module—a notoriously difficult course involving retrosynthesis that usually results in poor pass rates. The time spent listening to the presentations and marking the posters has been returned tenfold by the improved attitude to and performance of the students in the ChemII Organic module. Also, after the poster presentations, their approach to me, the ogre whom they perceived as preventing them from passing ChemII, became friendlier. In future years all students who register for the ChemII organic module (even repeating students) will be required to prepare and present a poster. Acknowledgment I would like to thank an anonymous reviewer for insightful and useful comments that greatly enhanced the quality of the final article. Literature Cited 1. 2. 3. 4. 5. 6.
7. 8. 9. 10. 11. 12.
Lagowski, J. J. J. Chem. Educ. 1990, 66, 279. Katz, M. J. Chem. Educ. 1996, 73, 440. Wruck, B.; Reinstein, J. J. Chem. Educ. 1989, 66, 1029. Clouston, L. L.; Kleinman, M. H. Can. Chem. News 1998, 50, 15. Towns, M. H. J. Chem. Educ. 1998, 75, 67. Landis, C. R.; Peace, G. E. Jr.; Scharberg, M. A.; Branz, S.; Spencer, J. N.; Ricci, R. W.; Zumdahl, S. A.; Shaw, D. J. Chem. Educ. 1998, 75, 741. Bradley, J. D.; Gerrans, G. C. J. Chem. Educ. 1971, 48, 174. Bradley, J. D.; Gerrans, G. C. Educ. in Chem. 1972, 9, 68. Bradley, J. D.; Gerrans, G. C. Educ. in Chem. 1985, 22, 74. Moore, J. W. J. Chem. Educ. 1989, 66, 15. Black, K. A. J. Chem. Educ. 1993, 70, 140. Sisak, M. E. J. Chem. Educ. 1997, 74, 1065.
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