Use these in the classroom in whatever way you choose. As I child in Elementary, we used to earn Highly Pleasings. I've also heard the term Warm Fuzzies used. There are HP's worth 1 point and Super Size ones with 5pts.
You can set up yourselves what the value of each coupon is and students can trade in their HPs or WF's for the coupons.
I've tried to create rewards that aren't too external like sweets, toys etc. This way they can eventually wean off a reward system and learn to love intrinsic rewards.