They can earn clovers ( or just boxes) on their cards. It is very simple. If they are being good you can have them color in a clover(box). I give out a lot during the day because it is an easy way to praise them. You may also have them cross out clovers too. If they finish their card before Friday they will give the card if it has no X out clovers. Then I will give them a prize. On Fridays I roll two dice and see who earns the prize. The must have that clover colored in to get a prize.
They get a new card if they finish the one they have before Friday. They just get a new one themselves. This is a very easy to manage thing. They also can move their pins up and down.
At the end of the day they get to color in a clover(s) on their cards depending on where their clip ends at.
On Fridays I roll a dice to see which clover gets a winning prize.