Last night on 60 Minutes, they featured the free website Khan Academy which can be found at: http://www.khanacademy.org/ This site features many watch and learn videos on a multitude of subjects. The Kahn Academy is a not-for-profit organization with the goal of changing education for the better by providing a free world-class education to anyone anywhere.
All of the site's resources are available to anyone. It doesn't matter if you are a student, teacher, home-schooler, principal, adult returning to the classroom after 20 years, or a friendly alien just trying to get a leg up in earthly biology. The Khan Academy's materials and resources are available to you completely free of charge.
The Khan Academy website offers over 3,000 videos that cover K-12 math, science topics such as biology, chemistry, and physics, and even reaches into the humanities with playlists on finance and history. Each video is a digestible chunk, approximately 10 minutes long, and especially purposed for viewing on the computer.
Teachers can also use this site for their classes and then check on student's their progress.