Instant Math Tutor
If your students are having trouble grasping the concepts of algebra or geometry, Yourteacher.com’s online service can help. Aligned with popular textbooks, the site has hundreds of videos that explain and show how to work out problems in middle- and high-school math. Each lesson has a summary and a nearly unlimited number of practice and quiz problems, which has answers that are fully worked out and explained. Try out the sample lessons and the first month costs $5; after that the service costs $29.50.