If you don't know about the Khan Academy, ...well you should, so know about it now!

If you are a K-12 teacher, you have to know about the free videos on the Khan Academy website.  They have a wealth of tutorials in science, mathematics and more.

There is an inspiring video of the creator of the Khan Academy on Ted Talks:  http://www.ted.com/talks/salman_khan_let_s_use_video_to_reinvent_education.html

Visit the Khan Academy here: https://www.khanacademy.org/