Thanks for all the input. I don't really want my DS to necessarily work independently, but he is in 1st grade and goes to a second grade class for Math and it is still very easy.

I am just thinking of and trying to get opinions on different options to think about, so I really do appreciate all the comments on the different programs here.

They have ALEKS at my DS's school but not until 3rd grade. I am definitely going to look into Khan and Alcumus. Thanks again.