Visual Multiplication

I'm always on the lookout for alternative arithmetic algorithms, and this one is very cool. It would be good for any teacher with the challenge of teaching a very "visual" student. And the idea of using a video to demonstrate it is great, since most math algorithms are processes that are better understood when seen done than when read about in a textbook.

For anyone who's interested, it's basically a more concrete version of gelosia or "lattice" multiplication. Its main drawback is that it relies on counting dots rather than adding number symbols. When they multiply 123 by 321, the numbers of dots are all small; imagine multiplying 97869 by 67898 by this method and you'll get the idea why this is a significant drawback.