We have gone through many different "reward" systems in our house to encourage good behavior. We used to do the sticker chart (get a prize once you earn a certain number of stickers for behaving or for doing a chore etc.), but that didn't work for us because I couldn't take the sticker away once it was given. After several versions of the chart, I had a great idea!!
I got 2 containers - 1 for Mia and 1 for Olivia - and they earn marbles for behaving, making their bed, getting a great report card and so on. On the other hand, when they misbehave, it is really effective for them to see me take away marbles. That is what was missing with the sticker chart!
When the jar is full, they get a surprise. A new toy or a movie; it works really great for us.