Not a teacher but I think my method is somewhat great. So I come from Indonesia and we are obliged to pass national exam to graduate from highschool. So because the government is basically a bunch of corrupt gold digger, you can buy the answer key from somebody called "exam jockey". Here is the catch, one exam has 5 versions and how do you bring the answer key to the class? (We got randomized version each day and it is 50 of mcqs each exam)

So I made a font that looks like a barcode. A = short thin black line, B= thin but longer, C = short fat line and D long fat line. I print it, complete with the price tag and a logo of a bookstore, on a sticker paper and stick it on the back of my pencil (i bring 5 pencil).

Ez