A fantastic way of rewarding achievement and behaviour in your class.
A great way to get the children in your class on task. Anytime they are on task, producing lovely work, answering a question correctly etc give them a "prize token" (a bit of blank paper).
They write their name on the piece of paper and put it into the prize jar. Throughout the day you keep reminding them "Now, who is doing their work quietly that I can give a prize token", and you'd be suprised how they stop talking and put their heads down and work.
The idea is to get their name in as many times as you can. Give them out EVERY TIME someone does something good. Give out lots too, the children get excited when they think they have a good chance at winning the prize.
Finally at the end of the day, pull out names out of the prize jar. If they have been really good give out a few more prizes, if they haven't been that good, warn them that no names may come out of the prize jar if they don't improve.
Try it. It works a treat!