Watch. Practice. Learn almost anything for free. With over 3,100 videos on everything from arithmetic to physics, finance, and history and hundreds of skills to practice, we're on a mission to help you learn what you want, when you want, at your own pace.
http://www.khanacademy.org/
downloading Khan Academy Playlist
http://www.youtube.com/watch?v=gZ3boWMwsoA
http://www.khanacademy.org/
downloading Khan Academy Playlist
http://www.youtube.com/watch?v=gZ3boWMwsoA