Khan Academy was begun by a very smart individual helping his niece out by tutoring her. He began to make videos and the rest is history.
Below is a selection of some of basic math subjects, to see the fulllist of topics click on "Math" at the top of this page.
"Short, tothepoint FREE math videos covering every topic inAlgebra, Geometry, Algebra 2, Trigonometry, Precalculus and Calculus."
"Brightstorm's Math Homework Checkerinstant answers to your specific math problems" Note: The homework checker appears underneath any Brightstorm math video.
A commercial product which offers many free math videos with lessons taught by a variety of teachers.
St. Louis Community College Libraries 
Florissant Valley Campus Library  Forest Park Campus Library  Meramec Campus Library  Wildwood Campus Library 
