Puffin pretty much covered it all. There is list of reality checks here, and you might find one you can use in school.

I like to visualize my body rising in the air, and I really believe that it's possible. If my body doesn't rise I am awake, if it does I am in a dream! Another good reality check is to look at a piece of paper, look away and imagine all the words changing, and look back. If they changed you are in a dream, if they are the same you are most likely awake. Make sure you are aware while doing reality checks, also. Instead of just doing the reality check look around and ask if everything looks/feels normal. Ask yourself how you go to where you were.

Anyway good luck!