Math (http://www.math.com)

If only you could subtract the ads from Math.com and add more attractive design, you might have an excellent place for mid-level and older math students to learn a lot. But there are so many ads that it's almost impossible to know whether you're clicking into content or just another ad link. Some of the main tutorials on basic math concepts are good, but most of them lack any kind of interesting graphics or interactive elements to keep kids' attention. On the plus side, there are some interesting links to other sites with fun math concepts, like tessellations and fractals. The few interactive games are generally good, but basic, and some require quite a bit of reading before being able to play, which may be especially difficult for younger kids. Unfortunately, this isn't a site most kids will likely want to explore for long.