I'm feeling less troubled about the organic chemistry problems I encountered recently. I returned the exams today and spent the whole period covering it. I was expecting some weeping and gnashing, but I got a lot of "Oh, now I understand." I also did a fairly in-depth review of what nucleophiles and electrophiles are. I hope it sticks.
I had a bit of success in my Biochemistry class. They are analyzing a dipeptide. The goal is to ID the two amino acids present and the sequence. To ID the N-terminus amino acid they functionalize it with a dinitrophenyl group. Then after hydrolysis under 6M HCl conditions they analyze it by TLC and compare to standards. In years past, we've had modest success for various reasons (usually student error). Today we batted 1.000 (which is really 100%).That made me happy.
On a related note, for any of you teachers, lab TAs or similar folk, have you ever given the entire class the same unknown? I have. They tend to freak out, but it teaches them to have confidence in their lab technique.