I wish I knew how to figure out if my child is learning in enough depth. Can my son just work through Aleks and get what he needs?
I recommend including some enrichment like Ed Zaccarro books along with ALEKS or regular elementary classroom math. Once you get to algebra AoPS and math contests are good forms of enrichment. Elementary and secondary math education is lacking in this country. I went through Calculus in high school and made all A's. When I got to college I realized that I learned a great deal of "how to do math" in K-12 but not much about "the whys behind the math." I figured much of that out in my college level engineering classes. It was not that the concepts were difficult; it had more to do with the way the concepts were presented.