My profs don't let you off if you say you don't know. They go to a question you do know then try to lead to the answer they were going for.
The work is so different from what I expected. You read 2 pages 2 twice, take careful notes, then go to class and have a prof point out slowly through questioning 20 things you didn't notice about it. Then at the end you find out the next case completely reverses or changes the rule established by the first, so all that work is just for historical interest. Then you read a 3rd case and you find out the second was the odd one, and the rule to take away is the one established in the first. It is like playing Where's Waldo, but with words instead of pictures and all the words are in a foreign language, so you have to translate them before playing.