I learned this from my center's director and it seems to work like a charm in my classroom of 4 year olds... The system goes like this... each child has a bucket with their name on it, and inside the bucket they have a "positive behavior" punch card. Each time a child is using positive behavior (i.e. using first time obedience, helping another child, or "filling someone's bucket" by saying or doing something nice) they get a card that says "Caught You Being Good!" and it goes inside their bucket. For every "good" card they have in their bucket, they get a punch on their punch card. When the punch card is filled up, they choose a prize from the "treasure box." It can also be used as a disciplinary tool, by taking cards out of their bucket when a child is disobedient. I love this system and the kids seem to like it too!