Math Lessons & Videos
Khan Academy is all the rage because they house a humungous database of wonderful & FREE teaching videos on a variety of subjects. Here are the links for the most common math topics. These videos are great for pre-teaching, teaching, re-teaching, and review: Algebra 1, Geometry, Algebra 2, Trigonometry, and Precalculus. They also have many other math courses, including AP Calculus & AP Statistics.
Great site with over a thousand FREE video lessons on Pre-Algebra through Algebra 2. There are also SAT, Common Core, and ACT Math videos! These videos would be great for re-teaching and review.