HELP! with an 4 year old that is acting out at daycare.?

Punishing him at home for something he did at school probably isn't very effective because his attention span is limited. He won't connect the two. The daycare teachers just need to continue to enforce discipline and it may just be a phase that he will grow out of. My son had a similar situation and after about 3 weeks he stopped being aggressive. It isn't polite and parents don't like it but it is normal behavior for a boy of his age. I'm sure your son isn't the only one who imitates this child. Your son doesn't act like this at home so I don't think that he is being led down the wrong path. He is just acting out and it is normal.