## Friday, March 18, 2011

### Math Teachers at Play 36

Welcome to the 36th edition of
Math Teachers at Play!

 How many rhombs can be traced on the edges of this figure?
36 has long been one of my favorite numbers, but faced with this carnival, it was hard to figure out why.  It's a square number that's a product of two squares, but that's not too rare.  (Why?)  It's the 6th perfect square and the sum of the first six odds, but that's not too remarkable.  (Why?)  It's the 8th triangular number, but not a Sierpinski step or anything... wait!  It's a square triangular number?  How common is that?  1, 36, then...?

 8+9+9+10... will numbers like that have a special property?
Number
Denise, the founder of this here carnival here, has an activity on Times Tac Toe at Let's Play Math.

Erlina at Mathematics for Teaching (formerly keeping Math Simple) has a nice introduction to integers based on sorting.

 Can you see the four 9-squares and nine 4-squares in this brick?
Guillermo has posts on addition and subtraction of integers.  He updated recently from his old wordpress domain to mathandmultimedia.com.

Marilyn at Mad Kane's Humor Blog had a Pi Day limerick.  Given Pi Day's proximity to St. Patrick's Day, that's a double score. Bonus: Math Jokes 4 Mathy Folks had mathy St. Patrick's jokes.

Pat blogged at Pat's Blog, hmmm, about Pi from a classic Venn illustration in 1888 to an internet meme cartoon from 2011.

John has fascinating info on a class of prime numbers called the Limerick Primes at the Endeavor.

 How can you quickly determine if 1926 is a multiple of 36?  Is it close?
Algebra
Mimi at I Hope This Old Train Breaks Down... has a complete activity on (beyond) composition of functions, adapting and extending an NCTM activity, and also an idea for a neat telephone function composition activity.  She's prolific, so poke around the blog while you're there.

Alexander, author of the amazing Cut-the-Knot, has a great discussion of inverse functions, relating three different Mathematics Teacher articles at the CTK Insights blog.

 How big is this 36 in real life? Why do you think so?

Geometry
Becky at Wide Open Campus has a quick little activity called Nature's Pattern Blocks.

Chris at M.O.B. has an activity on Mirror Imaging Monsters.  Arrrgh, reflectional symmetry.

Maria at Homeschool Math Blog has an excellent problem with a chord. Good challenge with a different perspective.

Connections
Katie has a travel site, Tripbase, with the nine most mathematically interesting buildings.  I might make it ten for either the Plaza de EspaĆ±a or the Alhambra in Spain, both of which have some great tessellations.  What would you add?

Cheong ponders Are You a Number? at Singapore Math.

Representation
Caroline at Maths Insider has a post on strategies for your visual, auditory or tactile learner.

Sue, writing at Math Mama Writes...,  use graphs to make connections to increase her understanding of trig identities.

I never got a chance to clean up and make pretty this 36 knot that I designed for this carnival.  Why on earth would I think that this somehow related to 36?

 Why would 36 degrees be newsworthy?

Teaching and Learning
Rachel at Quirky Mama has monthly math activities for preschoolers.

Maria at The Math Mom recommends a short post with 5 tips for not transferring your math anxiety or a long and serious post on if it's okay to be smart.

Peter has a collection of links to enthuse about math at Travels in a Mathematical World.  Peter is half of the Math/Maths podcast.

Jacob tackles memory vs. mastery learning at License to Teach.

Carson shared a nice graphic relating math to careers at When Am I Going to Use This?  But it's at an online education site, which Dan Meyer wrote quite forcefully against, in terms of predatory recruitment, at dy/dan.  He was writing specifically about the Top N lists.  What do you think?

The other issue to be on the look out for is the EduSolidarity online rally, March 22nd.  If you don't stand for something, you'll fall for anything.

So Long and No Longer
Sorry this was a wee bit late.  I had a busy couple of days between Knot Fun (Celtic knot activity on axioms) and a Tech Symposium presentation, for which I assembled this glog (interactive poster) about the Tech I Use.  See you next month inside Maths Insider hosted by Caroline.  Submit an article!

Mathy pictures made in Geogebra.  Other pix from Flickr - the photographer's name for each is in the file name.  And a special MTAP shout out to Leo Reynolds, who has got to be the most prolific number photographer in history.

1. Looks great! Thanks for hosting.
I posted a link, and now I'm ready to enjoy an afternoon of browsing...

2. Excellent post, as always.

3. Brain teasers are are also a great activity.

4. square triangular number? How common is that?

Not very common: http://oeis.org/A001110