Four on eight
FOUR ON EIGHT: Honestly, though we did, of course, get some odd and downright incorrect statements on the exam for the course I taught, I was happy to see the students surprise me. In a few instances they correctly wrote down things which I promised I would not examine them on (i.e. I told them they wouldn't have to reproduce equations, but some chose to) and a few comments which were true but I did not tell them which they either deduced themselves or picked up elsewhere.
It is gratifying that when one teaches, they actually learn! It's almost as surprising as having an experiment work the first time.