Just a regular page method

On top and on the bottom of the page there is a margin most of the times, cut out the margin from a notebook and write everything you need to know on it. On the day of the test just fold it up and put it between your watch and your arm, or in your sleeves. When you need it, fold it open and put the piece of paper underneath your test. Every time you don't know the answer just shove your test a little higher, so the answer shows. No-one will notice because the length of your test paper will only be 1 inch longer. When your teacher comes near just shove your test over your piece of paper. Make sure you don't leave it underneath when the tests are being picked up. Afterward, get rid of the evidence.