Two things. 1. Pretend that you're teaching someone else how to do it. You might feel dumb playing make believe at your age, but it used to help me, so I suggest trying it.
2. Make a cheat sheet, but DON'T USE IT. Guess what will be on the test (or your teacher might just tell you) and make a little cheat sheet with short, to the point answers. Then leave it at home. Just making it should solidify the knowledge in your head. Good luck!