Does he take notation? That helps so much in reviewing what happened afterwards. If you know something about chess, you may be able to spot some patterns. Maybe he's moving too fast?
Sometimes issues in chess are emotional, too, not psychological. I have seen kids lose due to overconfidence and due to being "psyched out" from a previous loss.
Ratings are awfully deceptive sometimes, so losing to a 200 might not be as bad as it sounds. And the 900 kid could have blundered badly. I find you can't learn much about the game from ratings and win/loss...have to look at the notation.
