Does he have a guidance counselor in school? If so perhaps the counselor can suggest some extracurricular activities for him during the year. Looks like he has summer sorted.
Perhaps he will be more motivated hearing the suggestions from a counselor instead of his parent. Since he is in 10th grade he most likely knows where his interests and passions lie, perhaps he will share this with the counselor if not with a parent.He may be unaware that colleges and universities expect to see evidence of a student's participation in extracurricular activities as well as good grades.
