C.W.
Is he getting enough sleep? My son is the same age and can get like this if he isn't well rested, especially with a change in routine. We remind him before he goes that he should have no time outs. If he has not time outs, we make a big deal of it and he gets a treat, like a popcycle, m&m or small candy. If he does get time outs, we remind him he shouldn't have. By the time he gets home, he can't remember why he got the time out so punishing, like no TV doesn't really work.