Braining Camp is a great supplement to your Middle School Math curriculum. It has interactive animated lessons covering algebra, measurement, geometry, numbers, probability and problem solving. The animations and virtual manipulatives are cleverly done to help students understand the problems. Assessment and progress tracking are included. Pricing is very reasonable at $10 for 2 months, $35 for six months and $50 for a year. A free trial is offered so you can check it out.