We didn't start there. I prefer the page much of the time, too, personally, and DS8 likes paper and pencil. But for helping a kid who's not quite getting the concept, the hands-on balancing idea is a pretty handy trick.

I would call the "Key To Algebra" series some pre-algebra leading to maybe high school algebra 1. It is very light on problem solving. But it does get into graphing, polynomials and systems of equations, so I think it's a good primer before AoPS.

Kriston