LearnZillion has tons of free video math lessons that end with a quiz. Those in themselves are not that big of a deal, but three nice things about them are that they are designed by teachers, are free, and that teachers can create “virtual” classes and monitor student progress on them.
As a non-math teacher and as someone who detests anything to do with math, I cannot vouch for the quality of these lessons. However, I’m still adding it to The Best MATH Sites That Students Can Use Independently And Let Teachers Check On Progress.
I heard about LearnZillion on NPR’s Market Watch program, and you can read/hear it here.