I don't know if this has been commented on up thread, but some local g/t kids are taking courses at Harvard Extension around age 14/15. Also, it looks like kids outside of the Boston area are potentially able to enroll in courses, or even in a MA program, at Harvard Extension online.

Eugenie de Silva completed a MA through Harvard Extension online (http://eugeniedesilva.com/eugenie-carys-de-silva). I don't know how common that method, but notice Eugenie is enrolled now in a PhD program through Leicester U (UK) online too.

Yes, Harvard Extension isn't Harvard. That's a given. However, it might provide some challenge that so many of us are searching for with our kids and be doable for some needing a more non-traditional path. From what I've heard, many of the faculty at Harvard or nearby colleges/universities teach at Harvard Extension and it's a small pittance of the tuition too.