This is an alternate to my scratch lottery ticket post: QR code prize tickets. Here is what you do:
1) Use a free QR code generator online to create the QR code. I used www.qrstuff.com . Use the plain text date type. No internet is required when the students scan the code with a smartphone or tablet.
2) Decide what your prizes are. Mine are 1 candy, 2 candies, +2 extra points, and 1 sticker.
4) Print them (on cardstock is the best!) and cut them up.
5) Hand them out as prizes!