Update on my little math guy (9). The past few months, his teacher has let him do whatever he wants for homework, with the result that he is now learning calculus (through Khan Academy and a Life of Fred book from the library). I gave him an Alg 2 end of course exam I found on the internet when I realized he was actually serious about trying to learn calculus, and he aced it easily. He likes calculus and finds it pretty intuitive.
He'll go for months without pursuing one of his academic-ish interests (programming, music theory and composition, and math), and then he'll really concentrate on one of them for a few weeks and be very productive. Some periods of time, he'll just play and be into Minecraft or making boardgames or writing his newsletter or something. In fact, I would say most of the time he's not pursuing anything academic (although if someone put a new math book or something in his hands, he would eagerly read it). I think the only reason he made progress in math was that there was some (very loose) structure to it (he had to do 20 minutes of anything math-related 4 days a week for homework). He's very happy this year and has a couple of really good friends. I never push him to do one thing or another (except the bare minimum of instrument practice and helping out around the house).
Anyway, I guess the current system is working for him. I have the feeling he wouldn't like a more formal course because it wouldn't be self-directed enough.
I still worry about the future though. He is really a pretty typical kid except for being good at math and having weird interests some of the time. For those with older kids, how did things go in middle school and high school? Has anyone tried NOT formally educating an advanced math kid? Or, if you did radically advance your kid in just one subject, did they still have a normal middle school/high school experience? Is there anything you would recommend or do differently? I also worry that the reason he's happy now is that he has time to do what he wants, and he'll be considerably less happy when he starts getting actual significant amounts of homework in middle school. He has never liked having to do what other people want him to do! (like most kids!)