My 8yo son's IQ (which is actually not reportable because of an out of whack processing speed index score) is 138. His GAI is much higher. He has been homeschooled all along and tests about 5 years ahead in math, reading, and language on various achievement tests. His writing is less advanced than this (I think) and is probably only about 1-2 years ahead.
I think gifted children generally need much higher level input combined with more grade appropriate output expectations. So this might mean using a text that is 5 grade levels ahead but output is oral rather than written for science and history. Math (even algebra) can even be done orally (ask me how I know). English gets a bit more complicated because for the writing piece the output is what it's all about. But still the literature could be more advanced and the writing less so.
Unfortunately, when you are working within the confines of a school (even a virtual school) the child needs to be placed at his output level. So for my son, if he were to use the K12 curriculum without modification that would probably be a 4th grade level because of the (ridiculous IMHO) writing demands.
My suggestion would be to get away from using K12 with the virtual school. It is difficult enough to adapt when using it independently (which we have done), I would think that it would be impossible to work with it effectively given the constraints in the virtual school.
