Alright both of these ways works perfectly and you will never get caught.
First, if you have a lot of writing, type it all out and print it in small font. Take a waterbottle that you buy in stores like crystal geyser or whatever(one that has a removable layer on the outside that has the name, and everything else on it.) Take the little later and detach it from the sticky part, be careful and sure not to tear it all the way around. After youve unstuck it, slide it to the very end and place the paper facing towards the inside of the water bottle and close the paper again and it will stick just like new. You can fit multiple pieces in there as well so can get a lot of paper. Go to class with half a water bottle, take drinks and look inside it while you drink or just keep it on your table.
The other way works if you have like the answers to a test. Take a gumwrapper and take the gum out. Write all the answers on the inside of the gumwrapper, put the gum back, put it in the case and take it out during test. Chew the gum and you can use the sheet. Its better than paper because if a teacher sees it you can crumple it up and throw it away just looks like gumwrapper.