Khan Academy: Free Worldwide Homework Help in Math

Former Hedge Fund analyst Sal Khan put homework help in math on YouTube for his cousins, and a funny thing happened.  Students around the world started responding that they appreciated the explanations, they understood.  The virtue of video help in Math is that kids can rewind to review.  There's no feeling bad for not understanding the first time.  Students advance at their own pace.

What started out as help for family has grown into a library of 2,100 videos and 100 self-paced exercises ranging from basic math to vector analysis, physics, chemistry, finance, and history.  The website is Khan Academy. 

The Khan Academy won Google's Project 10 to the 100 of ideas to change the world and is now an IRS-recognized 501c3 not-for-profit organization.