No, not yet. Have considered it before our alps trips the last couple of years, and nearly put them on a days course in morzine last year (they did not want to). Now I would definitely not send my 13 year old, having a hard job keeping up as it is! (Downhill only). May get some coaching for the 11 year old before we hit morzine this year, as he is not really a natural. He enjoys the alps (as he does uplifts only and is a lazy bugger) but sticks to the short blues at morzine/les gets.
Does your son enjoy it? It may just not be his thing. If he does, perhaps a course in a group with other kids? Or maybe meet up with other riders with kids the same age and they can play about and learn from each other.
Simone