This carnival has been published in Mathematical Palette, but the blog has been closed, so I decided to republish it here.

Below are the entries to the 55th edition of the Math Teachers at Play Blog Carnival.

#### Mathematics Teaching

Maria combines Halloween and mathematics for kids in *Friendly Ghost Odd and Even Sort* posted at Learning Ideas – Grades K-8.

Ali Muñiz shares a Geometry game on *The Making of Angle Find: A Geometric Game Discovery* posted at the Puzzle Zapper Blog.

Angie Eakland creates a clock activity that aims to improve the skills on order of operations at *What Time Is It?* posted at Coefficients of Determination.

Jennifer uses straws to explore 3-dimensional geometry in *Hands On Exploration: 3d Geometry with Straws* posted at Adventures in Mama Land.

Beth Schaubroeck shares a miscellany of mathematics resources for homeschooling at *Elementary School Enrichment* posted at Shaubroeck: Math.

Dan McQuillan introduces interesting mathematical activities for elementary school students at *Squaring the Superhero *in his blog.

John Golden presents an integer multiplication and addition game for middle school and high school students that provides some intuition for inequalities in *Greater Than* posted at Math Hombre.

Pat Ballew posts a beautiful Geometry problem that reveals a common student difficulty in *Student Difficulty with Geometry* posted at Pat’s Blog.

Tom de Rosa toys with the project idea of *What If You Lived in the World’s Skinniest House? *posted at I Want to Teach Forever.

Dan MacKinnon uses Generic Rectangles to introduce multiplication of polynomials posted at Math Recreation.

Denise of Lets Play Math introduces models in teaching multiplication in PUFM Multiplication Part 2.

#### Content Mathematics

Alexander Bogomolny presents a solution to a geometric puzzle from Plato’s dialog *Meno* in S*olving Puzzles with Socrates* posted at CTK Insights.

Proofs from the Book introduces the first supposed geometric theorem proved in *Thales’ Theorem*.

Dan Pearcy shares some of his learning in programming using GeoGebra to introduce infinite sets in* An Introduction to Infinite Sets: Programming with GeoGebra and Failing Miserably* posted at Teaching Mathematics.

Allan Canonigo discusses the proof of the Ptolemy’s Theorem posted at Mathematics and Education.

Shecky R provides an overview of Steven Strogatz amazing book the The Joy of x in* Joy to the Word (of Math)* posted at Math Frolic.

What would it take to fill the room with popcorn? This is faced by students in the Popcorn Problem posted at Math Circle Blog.

Mathematics and Multimedia discusses PEMDAS and the Common Errors in the Order of Operations.

This concludes the 55th edition of the Math Teachers at Play. You may submit your entries for the 56th edition here.

#### Recent Carnivals

If you missed the recent carnivals, please visit the following links.

## Interested to Host

If you are interested to host a carnival you may contact Denise for hosting the Math Teachers at Play or me at mathandmultimedia@gmail.com if you are interested to host the Math and Multimedia Blog Carnival.

*Photo Credits: Snappybex, Marcin Wichary, dumbledad, Sam, woodlywonderworks via Flickr*