The kid is one of the hardest working kids in band. While he'll never be an all-region level player, he is very very dedicated. If his microphone system has a volume modifier on his side, he can clip the mic to his bell to hear his own playing quite well. Make sure you sit him next to a kid who can relay/give instructions, or speak loudly, clearly, and slowly in his class. The kid will move a bit slower at first while they get used to the instrument, but if the kid wants to learn, they'll do just fine for you.