Yes, especially with a natural-born learner! Keeping up with a kid in the upper elementary levels could be harder, I suppose. My DS is only 6.5, not 9. But there are plenty of classes out there, both online and at HSing co-ops. Find a willing math major at your local college and you've got a private tutor. We're trying that with foreign language if I can ever get my act together to make the arrangements.

You don't have to teach it all, you just have to provide the opportunities for learning! However those opportunities come about.

Kriston