Can you just be honest with him, or do you think it will break his heart? You
don't want to hurt his feelings, or make him feel that he is being put down, I
understand. But, after telling him you chose the best, can you suggest, "That
when you see this kind of effort from him, you will consider choosing his work.
Until then, he has a lot of practicing and experimenting to do." Then, perhaps
you can suggest that you will help him where he is having trouble if he is
serious about being considered for any art competition?