I'd agree with ZS. If your child is up to the course demands, or if the instructor is willing to let him sit in on an audit basis, and benefit from the instruction and conversational practice without the written expectations, I would let him try. I was only a year or two older when I audited my first university course--a foreign language. Some other students from my program were your son's age when they did the same thing that term. I don't remember feeling the age difference most of the time, as I was interested in the language. Possibly more so than some of my classmates. I do remember one of my parents meeting with the professor, probably to reassure themselves that he would handle my placement gracefully (although the only thing I remember from the conversation was a discussion on seasonal allergies!).
