One valuable habit he should learn is to watch the road ahead for possible hazards like nails, screws, broken bottles etc. It's surprising how much trash ends up in bicycle lanes. It is less time and trouble to stop and clear the hazard than it is to patch a flat.
I agree that he should fix his own flats. That will stop a lot of it. At 10 he may not be able to dismount the tire but he can do the rest.