Delay Reactions, Hasten Understanding

In my early years of teaching, I would break the ice the first day of class by asking my students what they know about organic chemistry. Without fail, the first student to respond would say something to the effect of: “It’s really hard! I’ve heard that there are so many reactions to memorize!” A low murmur would commence among my students, signifying general agreement. I had long known that memorization was an enormous problem for students in organic chemistry, but after this scenario repeated itself a few times, I started to think that the perception students have, even before the course begins, must contribute a great deal to the problem as well. Students know that there are quite a few organic reactions for which they will be accountable, but the vast majority of these students have not heard about mechanisms or charge stability or stereoisomerism—important concepts that are necessary to make sense of, and eventually master, organic reactions. Consequently, it seems most students enter the course thinking organic reactions will be discrete pieces of information that they must know. With all of the success these students have had memorizing information in high school (and perhaps even in college), it’s no wonder many believe they can continue to have success doing the same in organic chemistry. This preconceived notion may not necessarily be detrimental, but it can be if, in addition, organic reactions are introduced too early. Why?

If reactions are introduced too early, students are hit with learning reactions and key fundamental concepts at the same. In this situation, students tend to have what I refer to as “reaction blinders;” they perceive reactions to be of the utmost importance (especially when thinking about exams) and everything else they are asked to learn comes across as a distraction. Consequently, students tend to focus on reactions to the exclusion of the things that might help them understand why reactions do what they do. To these students, organic chemistry develops into a long list of things to memorize.

This issue is exacerbated by the fact that it’s relatively easy to commit small amounts of information to memory. Those who memorize reactions from the very beginning tend to find things quite comfortable in the early going, but this is a false sense of security. The amount of information for which students are accountable grows extremely quickly, and eventually grows beyond what a student can memorize. From my personal experience teaching the course, memorization becomes overwhelming at around the fourth or fifth week. At that point, unfortunately, it is exceedingly difficult for a student switch tracks from memorizing to understanding. This would entail relearning several weeks of material in a different way while continuing to learn new material.

To tackle this, my textbook delays reactions to a little later than traditional organic chemistry textbooks. This gives students more time to process important topics that will help them better understand the reactions that are soon to come. Chapters 4 and 5 deal with isomerism in its entirety; Chapter 6 (acid-base chemistry) presents thorough discussions of thermodynamics and charge stability; and Chapter 7 introduces students to curved arrow notation and the idea of mechanisms, and also provides an overview of the ten most common elementary steps. Because these chapters are not convoluted with in-depth treatments of new organic reactions, students are not distracted and “reaction blinders” do not become a problem.

When I originally incorporated these changes into my teaching, I was concerned that I might not be able to cover everything I need to by the end of the year. To my delight, however, the exact opposite has happened; at the end of the year I now have a few class periods left over, which I devote to special topics. I attribute this, in part, to the fact that the material upfront doesn’t require a tremendous amount of time (see this post); by the end of the twelfth class period, I have typically completed Chapter 5 and Nomenclature 3. Additionally, I think it is made possible as a result of my students having much better foundation for learning and understanding reactions from the outset. They can see the connections among reactions (via their mechanisms) more clearly as we progress through the course, so we spend a lot less time on many of the reactions than we did in the past.

More importantly, as I had hoped, my students no longer spend a great deal of effort trying to memorize reactions. Chastising students for memorizing is a thing of the past. Now, after we cover a particular reaction in class, I will sometimes warn students of the perils of memorizing, and the common response is: “I don’t get it, what is there to memorize?”

-Joel Karty

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