Shortly after I began teaching, when I was still using a book organized by functional group, I came to dread the second exam of the first semester. The class would typically perform decently well on the first exam, but scores would plummet on the second one. I recently looked back at my records for a reminder: the final year I taught from that functional group book, the class averaged 72 on exam one and 60 on exam two. For lack of a better description, exam two would crush my students. I remember wondering if this issue was something specific to me and how I taught. But after talking with my organic colleague at the time, who was a seasoned veteran, I learned that this was a regular trend at my institution since long before I arrived. If it wasn’t just me, what was the problem?
In retrospect, I’m sure one major contribution to the problem was the large increase in difficulty of the material in such a short amount of time. Exam one primarily covered basic bonding, nomenclature, intermolecular forces, acid/base chemistry, and an introduction to infrared spectroscopy. Most of that material (probably all but IR spectroscopy) was review from general chemistry or was at least somewhat familiar. The material on exam two, on the other hand, was almost entirely new for every student, including conformational analysis, stereochemistry, reaction mechanisms, and the SN1/SN2/E1/E2 competition.
Although more demanding material on the second exam was certainly a contributing factor, I don’t think it was the only factor. I’m convinced that the decline in scores was also due to the nature of how my students approached studying. Most students would enter the course expecting to memorize and learning under a traditional functional group organization helped reinforce that expectation, especially in the first few weeks (see this post). Therefore, by the time my students were ready to study for the second exam, most of them had already committed to memorizing and found themselves beyond the point of no return. The trouble was simply that the ratcheted-up material on exam two was beyond what students could effectively memorize.
I wrote my textbook with this issue of exam two mind, incorporating some key aspects to help alleviate the problem. First is a more robust treatment of foundational topics on structure and acid-base chemistry than is found in traditional textbooks (see these posts: 1, 2), which gives students a better command of the tools necessary to understand mechanisms and reactions. Second, Chapter 7—an overview of the ten most common elementary steps—helps usher students into working with mechanisms confidently and effectively. And third, the discussion of nucleophilic substitution and elimination reactions, including the SN1/SN2/E1/E2 competition, is done over a couple chapters (8 and 9) rather than in a single chapter, giving students more time to digest what can be very challenging concepts.
I no longer dread exam two, even though the material found on exams one and two is comparable to when I was teaching from a functional-group-organized book: exam one covers through part of Chapter 5 and exam two covers through part of Chapter 9. I still see a modest drop in scores on exam two, which, over the last several years, has averaged about five points:
2013: Exam 1 = 79; Exam 2 = 74
2012: Exam 1 = 81; Exam 2 = 74
2011: Exam 1 = 79; Exam 2 = 74
2010: Exam 1 = 80; Exam 2 = 77
But that’s a lot easier to handle (for both my students and myself) than the 12-point drop from long ago.
One way to interpret this modest drop is that there is still an increase in rigor on exam two. Another interpretation is, with the average on exam one routinely being around 80, perhaps I am underestimating my students’ ability to handle Chapters 1-5, and that it’s time to start moving through those chapters a little more quickly.