I set up a race track on a bulletin board and have each kid get a laminated cut-out car to put their name on. Everytime they score an 80% or above on a quiz or test, they get to move their car one space around the track. When they reach the finish line (or go several spaces, etc.), they get a "freebie" homwork.
The "freebie" homework means they can change a quiz grade to 100%, not that they get to skip an assignment.
