# Rice, Rectangles, and Mathmagicland

Welcome to this week’s Math Munch!

Want to practice your math facts?  Want to help feed hungry people around the world?  Well, with Free Rice you can do both at once!  Every time you answer a question correctly, the website donates 10 grains of rice through the UN’s World Food Programme.  You can work on multiplication or pre-algebra, as well as vocabulary, flags of the world, and other subjects.  It’s good practice for a good cause!  What do you say?  Will you help?

Up next, meet Edmund Harriss.

I found him through his fantastic math blog, Maxwell’s Demon, but he’s also a visiting professor at the University of Arkansas and a mathematical artist to boot.  We’re going to take a look at his recent blog post, “the 2×1 rectangle and domes.”  I seriously encourage you to read the entire thing, but I’ll share a few highlights.  The 2×1 rectangle is called a domino, and when you cut one in half along the diagonal, you get a lovely triangle with nifty tiling capabilities!

Also, standard plywood comes in the same proportion (8’x4′), and they can be easily combined to make several types of domes, as you can see below.  Click here to see how a hexayurt is built.  Edmund goes on to talk about the truncated octahedron, and how we can use its shape to design these domes.  How amazingly clever!

Finally, let’s take a look at a classic Disney film, from 1959 – Donald in Mathmagicland.  Donald Duck, on some sort of hunt, finds himself in a very strange place, surrounded by numbers, shapes, and patterns.  The trees even have square roots!  Mr. Duck meets “The True Spirit of Invention,” a mysterious voice that leads him (and us) on an adventurous trip through Mathmagicland.  If you skip to 16:48 in the video, you can learn about Billiards, a game played on the 2×1 rectangle!  How fitting!

Bon appetit!