My soon to be 3YO DS attends pre-school two mornings a week. He has been going since February and every time I leave him he screams and cries. I linger outside to check and he is usually fine after a couple of minutes but I'm concerned as it has been going on for so long. When I pick him up he always says he has fun but he doesn't really talk about what he does there and doesn't mention the names of any other children. This is odd as he is usually very chatty. The staff all say he is fine. What do you think?