Stimulant meds increase the capacity to focus on boring and repetitive tasks, but they aren't a substitute for a good educational fit, and they don't necessarily make you less impulsive - they sometimes make impulsive behavior worse.
It may be that he'd rather work on something engaging, like drawing, than attend to work that he doesn't see the point of and that is far below his level, even though he knows that he is going to get in trouble for it. The reward of doing something that is actually interesting might be worth it. I feel for him.
