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 "Learn almost anything for free." That is
the tag line of the Khan Academy. While the claim is a bit of a stretch, especially
when you need to delve below surface level, they do have over 3,300 videos on everything
from math to physics, finance, and history. According to their website, in August
2004, Sal Khan began remotely tutoring his cousin, Nadia, who was struggling with
unit conversion. Soon, Sal also began tutoring her brothers as well. He became so
popular that he started recording videos and posting them on YouTube. More and more
people kept watching, and Sal has continued to make videos ever since. Khan eventually
drew the attention of Google ($2 million grant) and Bill Gates ($1.5 million grant).
The rest, as the saying goes, is history.
 RF Cafe visitors might be particularly interested
in subjects like circuit analysis (4 lessons), capacitance, magnetism (12 lessons),
electric motors, electrostatics, Doppler, optics, and fields. You might also like
watching the video lessons on momentum and torque, friction, gravity, thermodynamics
(5 lessons), Newton's laws , and fluids (12 parts).
For a little nerd fun watch the video on what the takeoff roll for an Airbus
380 would be for various weights or how fast a baseball would need to leave the
bat of a hitter at home plate to clear the Green Monster at Fenway Park.
 Some lessons do go well beyond introductory
concepts by including vector products and calculus in the presentation. Magnetism,
for example, uses cross products in the high numbered lessons.
 If you need a math refresh, maybe the lessons
on complex numbers would be helpful. If you're doing statistical analysis, then
the box-and-whisker lesson might help. There are modules for probability and statistics
as well, and for about a hundred other topics including trigonometry, geometry,
factoring polynomials, exponents, logarithms, linear algebra, and matrix operations.
Finally, if you are involved in the business side of the company, lessons on
microeconomics and macroeconomics cover topics like the business cycle, fiscal policy,
inflation and deflation, investment, and money supply.
Even if these video lessons are of no interest to you, they might be just what
your kid is studying in school. The fresh insight from a different instructor could
be just what he/she needs. It's worth a try.
The August 2012 edition of IEEE's
Spectrum magazine ran an article on Khan Academy if you want more
information (other than just visiting Khan Academy's website).
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