I gave my second exam of the semester a few days ago. One of the questions presented students with the reactants, conditions, and product of a Robinson annulation reaction. The question was worded: “Draw the complete, detailed mechanism for the following Robinson annulation.” After I collected the exams, I returned to my office to find a student waiting for me, who had just moments ago finished the exam. She didn’t look happy, so I asked what was troubling her. She said, “In class last week, you told us we didn’t need to know the Robinson annulation, but you put it on the exam!”
I immediately corrected her, saying that what I had said in class was I was not going to hold students accountable for predicting products of a Robinson annulation on the exam, and that the question I wrote didn’t violate my promise. I reminded her, furthermore, that on exams, I always try to have at least one significant question that goes a little above and beyond what is familiar. Instead of the Robinson annulation reaction (which we touched upon, albeit very briefly, in class), I could have asked for the mechanism of another reaction that they had never even heard of. This didn’t seem to appease my student at all. She responded, “But I didn’t study the Robinson annulation!” I said, “I’ll tell you what…. Let’s take a look at what you did.” I found her exam and turned to the page with the Robinson annulation. She nailed it! Her mechanism was flawless.
This experience taught me two things: (1) With a solid mechanistic foundation, students are often more capable than they think they are, and (2) the next time I do something like this, I need to leave the name of the reaction out of the exam question.