Family of 6 in PA

My boy is still in school. What can I say? He likes it there. So if that's what he wants, let him go. I don't know if the teacher gave a pep talk or what today. He was very excited while showing me all the papers he brought home. But then followed hours of running, jumping, screaming, throwing, destructive behavior and the other kids got hurt a couple times and I lost my temper more than once. He was nuts! I didn't ask him if they got to go outside today or anything. I can't think of anything here that triggered his behavior. I don't know why he gets like that.