We just subscribed to Dreambox. DS5 has zoomed through lessons and really impressed DS8.

DS8 on DS5 "Once he stops progressing so quickly we'll know the level he should be at in school. His work needs to be challenging but doable. I'll print out his grade level and take it to his teachers (DS8's former teachers who adore him) and get them to adjust his work level so he isn't sitting around doing easy stuff."