blackcat, you might try this report about enVision: http://ies.ed.gov/ncee/wwc/interventionreport.aspx?sid=618 Our district uses it and I think it's ok, though I've seen a few worksheets that required some non-math-related knowledge to get a correct mathematical answer which I felt might be unfair to some kids. FWIW the web archive page you linked seems to be dated 1999.