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# Category: Math for Elem Teachers

## From 360… Musical Pi

Many college students (and some of you) are fond of playing computer games like Guitar Hero and Rock Band. So they might really appreciate this post about Musical Pi from the 360 blog. A summary: Jon Turner (professor of musical composition) has composed a suite based on the digits in the decimal expansion of the number pi. Listen here! (mine played in Quicktime) A couple applications of this one for the classroom: Even algebra students know what pi is. It might help them to appreciate the randomness (and thus irrational nature) of the decimal expansion. The drum accents the distribution of zeros in the decimal expansion. In Math for Elemtary Teachers, we teach alternate bases. Here is a great example of a practical application of that… mapping base 10 to base 12 so that it will correspond one-to-one with the chromatic musical scale. For students that are interested in music composition, send them to the blog post on 360 to read more about how both math and composition were used to write the song. I’d love to have a set of these “songs” to illustrate decimals by sound. (in case anyone is feeling especially energetic today) pi (irrational) e (irrational) 1/5 (rational, one digit… period… BORING!) 1/3 (rational, one repeated digit… hear how boring it is) 1/11 (rational, two repeated digits… still boring) 1/7 (rational, six repeated digits) sqrt(3)...

## TED features Mathemagics

This little 15-minute TedTalk, Arthur Benjamin races calculators from the audience doing the calculations in his head. He is very entertaining and I think students would enjoy the presentation, since they are often under the impression that nobody has every done calculations without a calculator. He squares a random 4-digit number from the audience in his head just as fast as the calculators. For those of you that teach probablity, he does a neat trick guessing the missing digits of 7-digit numbers (this is somewhere around the 7-minute mark). For elementary ed, there is a nice “number” on guessing the day of the week when someone was born based on the birth date (8-9 minute mark). For you algebra teachers, he does the square of a 5-digit number, going through the thought process out loud (starting around the 11-minute mark). Cleverly, he squares the number by breaking it into a binomial:(57683)2 = (57000+683)2 = 570002 + 57000*683*2 + 6832 I’ll let you work on that one in your head… Possibly Related Posts: Bringing the Real World to Your Math Class Every Day Group Exploration in Math WolframAlpha Facebook Report Level Up: Video Games for Learning Algebra Coming out of the Closet: I’m a Game...

## African Fractals: A TedTalk about MATH!

Ron Eglash has a wonderful newly posted Ted Talk on Fractals, he discusses: Cantor sets Helge von Koch’s variation on Cantor sets Self-similar structures in nature Royal insignia (rectangles within rectangles) African village which is a ring of rings Circular and four-fold symmetry use in different cultures Algorithms and the relationship to learning stories Optimization for building african wind fences Bamana sand divination (random number generator from the 12th century) Every digital circuit in the world began in Africa… you’ll have to watch to see the reasoning Usefulness of using heritage-oriented mathematics to motivate minority students to learn mathematics Self-organization is in the brain, the Google search engine, and why the AIDS virus is spreading… the African methods of self-organization are robust, well-established and should be studied Eglash’s website, Culturally Situated Design Tools, contains programs and applets that highlight cultural heritage. There are LOTS of geometry references on the website, including several cultural references to Cartesian coordinates (navajo rug weaver, graffit grapher, etc.) for those of you teaching algebra. You could easily show this video in your class if you are teaching something where it might be appropriate. Total running time is 17 minutes. If you go to the TedTalks website for this one, you can download the whole video (in case you don’t have Internet in your classroom). I think it would take a little while to work...

## Math Games at Interactivate

I stumbled across a nice website last week called Interactivate with 140 (or so) interactive Java-based activities for algebra, geometry, probability, statistics, etc. Many of the activities are modifications of other activities, but still there are at least 30 unique game-based activities here to help your students learn. I particularly liked “Algebra Four” (a play on the game Connect Four). I am teaching my algebra students all about solving equations right now and this would give them some good practice. The student can choose the level of difficulty (one-step, two-step, distributive, etc.). So conceivably, a student could first play at the one-step level, then the two-step level, then add the distributive property, and work their way up. This is a two-player game, which is really the only drawback, as a student at home would have to play against themself (or convince someone else to play an algebra game with them… hmm… unlikely). I do like the timer, which would encourage the student to get faster at solving equations. And if a student doesn’t want to play against the timer, it could just be set for a high time. Another nice game here is the “function machine” like we’ve seen in textbooks, only this one is really a machine where you (or the student) inputs values, and it (the machine) processes the values and outputs them. The “game” here is...