I just recently had the same concerns (not quite as fast as your child, which provides me some relief.) I read the following articles,
http://mathmomblog.wordpress.com/20...ration-enrichment-and-the-calculus-trap/http://www.artofproblemsolving.com/Resources/articles.php?page=calculustrap&
and have since slowed things down quite a bit and am enriching much more, rather than simply advancing. For example, even though my DD has long mastered basic addition, subtraction, multiplication, and division, I have her play 24 as her math time some days. If you are not familiar, it just gives you 4 numbers that you need to somehow make into 24. She enjoys it, and I think it gives her a deeper foundation. I've also purchased the Heuristic Model Drawing workbooks from Singapore math, they are a great enrichment, and might be doing the mental math enrichments as well. I also plan on having her do Alcumus online math, which provides a less direct route to Calculus. So she will do some probability and number theory before she heads to Geometry, Algebra II, etc. Duke TIP also offers some great math courses, one of which is decoding secret codes, which is fun, while mathamatical.
I think gifted children can absorb at a very high pace, but I'm not sold on the fact that they should do it as fast as they are able to. What I've decided to do is to slow her down as much as possible, while still maintaining a challenge. Wider and Deeper is much better, in my opinion. So while I refuse to "coast" and simply wait for the others to catch up, I'm trying to find different scenic routes to take than the straight standard curricula.
