Lots of pieces here... If school isn't challenging, at some point they can develop the perspective that school is wasting and or stealing their time. If they are sincerely interested in learning, then the hypocrisy of a school claiming to be a place of learning can be nerve-wracking. I'd suggest looking for some of the articles about underachieving, because that may be the trajectory.
I hated most criticism as a kid; my DS6 likes help but criticism or anything repeated to him gets on his nerves. I had my own strange (and usually effective) ways to get from point A to point D, and critique involving telling me to do B then C before D would drive me insane. It's a peculiar art to offer a critique that doesn't tromp on a personal process. If they have the same sort of perspective, then the biggest sin to be aware of is trying to tell them what they think.
