Prodigy Just discovered this, and we're loving it. It's more practice than teaching, but the "gamification" is way better than, say, Dreambox. We're finding that it makes a nice complement to Dreambox and Singapore Math, we bop among the three of them as we like.
The only problem for us is, DD refuses to let herself lose! So if it tries her on something she hasn't learned yet, she refuses to give wrong answers and demands that I teach it to her on the spot. This morning I tried to give her a lightning-tour of reducing fractions, and it stressed both of us out, but she
would not let it go. (On the plus side, I now have a child who is highly motivated to understand fractions.)