Designed for students in kindergarten through high school, this website features thousands of interactive arithmetic lessons. It gives immediate feedback while the student is completing worksheets and provides over 26 mathematical subjects, all for free.

This is a very unique site to learn math. Not only does it create games for students to interact with, but it also creates entire story lines. Players proceed on missions in a strange world where the ultimate power consists of mathematical skills and knowledge. In order to save the world, players must solve math problems. And did I mention that it's free ... ?