White/Blackboard or Environment Cheat

If you have one of these teachers who have stuff written all over the board and it's full of due dates, random stuff, and funny notes to the teacher from students, this is a bit risky but extremely helpful. Before class, preferably when the teacher is out of the room, write down some acronyms or stuff to help you remember answers to the test. If you are really daring you might just be able to conceal notes between lines or in corners. You can also do this by writing on the floor, the wall, behind a bookcase you're near, etc. It also can be helpful if your teacher is blind, and won't easily see the notes.