How I improved my class performance in organic chemistry

As you can see from the graph, my classes have improved their scores on the ACS organic chemistry exam. How did I do it? On reflection, I think I did several things that combined to improve the scores…

Let me digress on teaching. Thinking is dependent on physiological structures in our brains (neural connections). A teacher has little control over creating changes in someone’s brain, compared to students. Note that I said little control. I don't think anyone can make a connection by desire. Even a student will be discovering how their brain works (not all students are equal).

I think there are two things I could control, incentive and practice. First of all, I gave a quiz or an exam everyday of class. If you did not prepare for class, you would not do as well. So, the points are there for incentive. I have no doubt these quizzes and exams were not popular with the students, however I knew that if I wished to have the best possible scores, I needed to have the students practice solving problems (thinking organic chemistry) as much as possible. By thinking, students would create the neural connections they would rely upon for the ACS exam.

For homework (practice), I learned much more slowly. When I began teaching organic chemistry, I had taken over a class for someone who was ill. I tried to carry on the policies already instituted. One policy was to check homework. The class used a standard textbook and solutions manual. Hence, the homework had the appearance of the solutions manual. Even though I provided mechanisms in class, I found few students could solve problems by writing complete reaction mechanisms. Asking students to write mechanisms on quizzes and exams was generally a grade reducing activity.

My first adjustment was to do away with collecting homework. I began by using the exact problems that were included in the homework on the quizzes. While this required effort, it did not require thinking. The quizzes also included problems that were analogous to the textbook homework problems. My first change was to begin to give those problems as part of the homework and I would use some of those problems on the quizzes. While this required greater effort on the part of the students, it also was not universally effective. More on this later.

I had a discussion with a colleague about how few students that learned organic chemistry ‘the way he and I had’. His advice was that students didn't know how to study. I took that as the next challenge, I would show them how to study. This presents my next awakening. Two weeks before an exam, I gave the class five reaction mechanisms. I advised them that these exact problems would be on the exam and that they should know them. Furthermore, I advised them that since I had given the solutions before the exam, I would grade them more harshly. Although partial credit could be earned, each problem could not have more than a three point deduction (out of six).

I anticipated a win-win situation. The student would be happy because they would know the answers to the problems and I would be happy as students would know the reaction mechanisms. What I was not expecting was that nearly half of the class had zero points of the thirty points on those problems. It took me some time to discover a plausible reason for this result. While I could have guessed that superficially, students were unwilling to study enough to learn the mechanisms, I surmised that many of the students did not comprehend the logic of the mechanisms and were thus unable to write them from memory. An analogy I suggest is that if you had to memorize the Gettysburg Address, it would become increasingly difficult if the language of the address is changed from English to another Romance language or finally to Chinese. In Chinese, all logical connection between the characters and meaning will have been removed and thus it will have become extremely difficult. This is why I believe many of the students did so poorly and I discussed this result at an ACS meeting.

My solution was to write worksheets which presented the problems at different levels of difficulty. By doing so, students could first learn the logic of the reactions and then by repeating that problem with more information removed, they could build on that simpler version. The final problems were similar to those in any textbook. Those worksheets were adapted into the book A Guide to Organic Chemistry Mechanisms (originally titled The Language of Organic Chemistry).

Let me return to my quiz strategy. Originally, I used the quizzes to check that students did homework assignments. I usually had questions that varied from the inanely simple to questions that might take students several trials to master. The simple could be answered simply by virtue of having read an assignment while reaction mechanisms may have been discussed in class or present on a prior quiz. For example, I found it useful to ask students to write resonance structures with curved arrows on several quizzes. I also used problems that were assigned from Organic Chemistry by Paula Bruice.

I must acknowledge some murky thinking at this point. While I was transitioning my class to mechanistic thinking, I had not made a total commitment to it. I did not require mechanisms for problems in Paula Bruice. Since students had a solutions manual for the textbook problems, they did could determine the product without using a mechanisms. That was my objective in writing the supplemental problems, to have problems that were similar to the textbook problems but which students had to figure out (mechanistically). I usually used two (out of four) of the supplemental problems on the quiz. The remaining problems were either from Paula Bruice or similar to those assigned. I thought the demands on students were not great.

After the exam in which the mechanism problems were given before the exam, I began to change the supplemental problems. Since I was handing out mechanism worksheets, I began to write problems that used the worksheet mechanisms and to ask for mechanisms on the quizzes. Over time, I continued to increase the number of supplemental problems and ask for more and more mechanisms. Since I had collated the worksheets into a workbook, I was able to better coordinate the material from the textbook, the workbook, and the supplemental problems. You can note in the graph that class performance had improved significantly.

It was at this point that I made another discovery. I had succeeded in converting my class to mechanism based instruction. The supplemental problems helped to reinforce a mechanistic path to their solution. Students continued to complain that the supplemental problems did not have solutions. Finally, I realized they were correct. Since my questions now focussed more on how the product formed and not what will be the product, giving the product to reactions would help the students. Thus, I began to write the supplemental problems with the products. Therefore, by virtue of asking students to write mechanisms for problems, students were better able to write mechanisms because they could arrive at the correct product. I think this change was the most complete in the 2008 data in the graph. I cannot say the 2008 data reflects that mechanistic change or whether that class simply had higher achieving students.

I would like to summarize my interpretation of the salient points of my teaching that I think contributed to the percentile increase on the ACS exam. First of all, the ACS exam focusses on the fundamental aspects of organic chemistry that mechanisms are well suited to answer. The workbook (A Guide to Organic Chemistry Mechanisms) succeeds in enabling students to write mechanisms. I focussed on asking students to write mechanisms. I continued to give five mechanism questions (out of 5-8) on my exams and I announced them before the exam. I gave mechanism problems that were similar to those in the workbook. In short, I tried to enable students to solve problems so they would be able to solve problems. I succeeded in making the problems easier so they could build the neural connections necessary for solving problems.