It's very important to have a solid alliance with the school. Establish an incentive system with the school, whereby your son is 'rated' two or three times each day in regards to his adherence to classroom rules. For each rating period when he succeeds, he earns some reward (TV time, video game time, 'treat', e.g.). For any period he does not conform to the rules, he will not earn his reward and he should also have some period of time out (e.g., 10-15 minutes).