I haven't read the rest of the responses to you so I might be redundant. As an artist I came to realize quickly that I did not like to be told what to do. Art for me was a freedom: freedom to explore and try new things, but art classes can really restrict. At one point I thought about Commercial Art and even took a class in it. I hated it! Then when I took studio art classes I started with a teacher who was all about freedom... no restrictions and loved it but the next semester I had a teacher who limited our supplies and insisted on black and white. I was furious and out and out refused to conform. I drew and painted during his class and always with color. I could have cared less if I got the biggest F. No one was going to tell me what I could and couldn't do when it came to my passion.
Perhaps because your son has talent and clearly a passion for some form of art he is rebelling with these preplanned activities. A sign, for me anyway, that he has a lot to offer.
BTW, I never got an F in the class. What I got was respect. I was the professor's favorite student by the end and when I took an advanced drawing class from him later on he would devote classes to critiquing my work.
I don't know if his art teacher is open to suggestions but you might be able to convince her to take an interest in what he is interested in. This might sway him. You also might want to look around your community for local artists. He might enjoy getting to know some of them and one might be willing to take him under their wing.
