Functional Groups, Mechanisms, and Memorization

I began teaching organic chemistry some 11 years ago at Elon University, a moderately sized liberal arts school in central North Carolina. Like many professors just starting out, I was eager and committed to my students’ success. I knew that mechanisms were the key to this success because focusing on mechanisms worked for me as an undergrad: Mechanisms allowed me to truly understand organic reactions rather than just memorizing them. Mechanisms helped simplify organic chemistry in general, showing me how seemingly different reactions are in fact related. So I focused heavily on mechanisms in my lectures, often taking 20 minutes or more to pick one apart.

Despite my efforts teaching and promoting mechanisms, I found in my first two years that the bulk of my students decided that mechanisms were an inconvenience. When studying, they spent tremendous time memorizing stacks of flash cards. It was therefore not surprising to me that the majority of my students struggled. Overall performance was poor (average 40^th percentile on the ACS exam), morale was low, and student attrition was high throughout the two-semester sequence (about 55 percent). Something had to be changed, but what?

It occurred to me that if I was expending much effort teaching mechanisms, but my students effectively ignored them, then perhaps part of the problem could be intrinsic to the way that the material was organized! I was teaching out of a popular book that organized reactions according to functional group—a chapter on alkyl halides, one on alkenes and alkynes, another on alcohols, and so on. Could such an organization be sending a strong message to students that structure should be the main focus, not mechanisms?

I decided that if mechanisms were the key, then I needed to make mechanisms the central part of a logical and coherent story. That story needed to begin with the fundamentals of structure and stability, and should then transition into the basics of mechanisms before going into complex reactions. And in order to maintain focus on mechanisms while discussing reactions, I needed to make sure that reactions that proceed by similar mechanisms were taught together.

I instituted this new organization in my third year of teaching the course. I kept the same textbook but rearranged the topics accordingly. In doing so, portions from the second half of the book were taught in first semester, and vice versa. It was considerable work on my part, but worthwhile. Student attrition dropped to 45 percent and the average score on the ACS exam rose to the 55^th percentile. These numbers have steadily improved as I fine-tuned my presentation.

Now, 11 years into my teaching career, student attrition in my course has dropped to 17 percent, and the average score on the ACS exam is over the 70^th percentile. Many more students are completing the organic sequence, and collectively they are doing much better. And I scarcely ever see any flash cards.

— Joel Karty