Wow, this topic has taken off pretty good. Well, I guess I will come on in now.
My adult classes are for those 14 and over, with some exceptions going both ways. Personally, I have found that I think I like teaching teens (15 and up) the best.
Younger kids just aren't usually tough enough for my regular classes, and they typically require much more instruction to understand the material being taught (and I have taught students from 3 year olds on up to mid 60's). Alot of adults are so set in their own theories and ideas that it can be harder to get them to see the different options. Teens are just in the middle. They understand pretty quickly and are in a good stage in life physically, they have many of their own ideas but can be pretty receptive to change in those ideas if approached properly. Sure they can be egotistical, defiant, etc., but if approached properly and treated as growing adults, they tend to listen real well. I make sure to give them respect and don't treat them as children. On top of all that, I feel I can make a differene with them. They are in a difficult stage in life - dealing with peer pressure, drugs, sex, gangs, fighting, education, dating, work, etc. If I can be of any positive influence on any of that, then GREAT!! Some of my best students came to me as teens.
Well, I could ramble on and on, but I won't. I just got back from an awesome stickfighting/knifefighting class with a visiting GM of another Art and am pretty amped still.