A Marble Jar can become a powerful tool for encouraging on task and positive classroom behavior. Place a jar on your desk and lay out the rules for the class.A marble goes into the jar each time the teacher wants to reward the class for positive behavior. As a teacher you can use the marbles to support the behavior that you find needs the most support--it can be a mix of academic and social behavior, or just following classroom rules. Perhaps you want to reward a particularly good response to a question. Be sure to name each thing you are rewarding as you reward it: i.e. "I really like how Jeremy remembered to raise his hand when he needed to sharpen his pencil. Thanks, Jeremy (plunk)" Or it might be for the whole group: "I'm really impress how you guys got your independent reading out quickly and quietly. I think that's good for two marbles. (plunk, plunk.)"
Decide ahead of time what your whole class reward will be. If it's a large jar and you can afford it, you might promise a pizza or ice cream party. You might have a movie day. Be sure to check with your principal to find out if it is an acceptable reward. If your principal is seeing the results he or she will probably cut you some slack. Be sure that the reward will really motivate your kids. It can be as simple as extra recess time (ask the principal) or as elaborate as a party. You might be able to co-opt the help of the parents in your class, as well.
One of the things that makes this method powerful, is that it encourages students to support each other in appropriate behavior. They will shush the talkative students, they will encourage the slow student to get his work done. It has the downside of putting peer pressure on children who find complying difficult. Give marbles for students who support the child who doesn't do well with compliance, and give marbles for the challenged child when he or she makes an improvement. Be sure you're clear that harassment and bullying is never appropriate, even if they are frustrated by the behavior of a classmate.
I first saw this technique used in an inner city Toledo school, in the Old West End. I subbed in another class earlier which was a real nightmare, but the class with the marble jar was a delight. The teacher used it consistently and the students understood what was expected, and knew they were being rewarded!
I have used the marble jar as a pastor at confirmation camp with 13 and 14-year-olds. I have also used the marble jar as a Sunday School teacher. It works!