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.

3)  Make the tickets.  Here are my templates: QRcodetickets Word document  |  QRcodetickets PDF file.

4) Print them (on cardstock is the best!) and cut them up.

5) Hand them out as prizes!