We just started homeschooling here and with DS9 it is the same thing. The one area I see lacking is writing but this is tough as it is the one thing he least likes to do. Using the computer alleviates this and now he is happy to do some poetry etc. and we recently "adopted" a US Soldier and he is writing to him.
I actually just decided to ask him what he would like to learn and how he would like to go about it and we go from there.
I agree with CFK, if your son is enough ahead that you don't have to worry about meeting any state mandates then just relax and see what he would like to explore.
