We have something here for whatever science you teach!
All links are organized by category.
CrashCourse - https://www.youtube.com/user/crashcourse/playlists
Tons of awesome courses in one awesome channel. Check out the playlists for past courses in physics, philosophy, games, economics, U.S. government and politics, astronomy, anatomy & physiology, world history, biology, literature, ecology, chemistry, psychology, and U.S. history.