Only three months away from the 10 year anniversary. Where does the time go? How much playful math is that we've shared? Thanks, Denise! (Gaskins, the founder & still organizer of this here carnival.)

117 is a pentagonal number...

... what is the next Math Teachers at Play that will have a figural number?

117 is the smallest possible length of the longest edge of a perfect tetrahedron with integral edge lengths. Its other edge lengths are 51, 52, 53, 80 and 84. Perfect polyhedra are sometimes called Heronian. The faces of these have a special property. Can you guess? (I may have made a GeoGebra applet to get that image, if you want to play.)

I haven't had the chance to make it in GeoGebra yet. But Simon Gregg, the host of last month's carnival, has been making some spiffy tetrahedra in GGB.

117 is a difference of squares and a difference of cubes. Two cool!

I called out on Twitter for any new bloggers who would be interested in being in the carnival.

Jill Price is just starting to blog at diymiddlemath.blogspot.com. First

Jennifer Gibson writes at thinkthinkmath.blogspot.com. Lots of neat blocks and visual explorations.

Erick Lee suggested a Joel Hamkins post with some awesome ways to use orthoprojections (direct views) with learners to amp up the spatial visual learning.

Paula Beardell Krieg suggested 5 excellent Math Play activities, so she is my unofficial cohost of this carnival. Suggestion number 1: play with rhombi. Find more on all of these plus, at her blog, bookzoompa.wordpress.com. (Where I am enthralled with her calculus post.)

If you have suggestions for next month's, send to the Math Mama, my bud, Sue VanHattum or share via the form at the Carnival home page. Sharing in the carnival, or hosting, is a great way to increase connections in the #mtbos/#iteachmath community.

Do you know about Joseph Nebus' Reading the Comics posts? He reads them all so you don't have to!

*Plus*he's hosting MTaP in 2 months.

Denise shared a riff on a Marilyn Burns post, math debate on adding fractions. I think she means this post about how 1/3 + 1/3 = 2/6. Contrary to the rest of the internet, read the comments!

Paula's 2nd: Pop Up Cards

Harley Davidson engine: Milwaukee 117 |

Fawn Nguyen is cleaning house. Throw it all out!

Another Simon Gregg post, this on multiplication and Cuisenaire blocks.

Dan Ashlock has a nice connection between a class of puzzles and proof in math.

Solenne Abaziou on the connection between persistence and open ended tasks.

Paula's 3rd: fraction books. I think trying to make her zero to one image might be how I Twitter-met her!

Jenise Sexton writing powerfully on 'I hate math.'

Mike Lawler et filii investigating irrationality, inspired by a Mathologer video. (Part 2) Plus pentagons, so on theme."At some point, it isn’t our words that change the behavior and mindset, it’s our actions, passions and desire to do the right work." - Jenise Sexton

Junaid Mubeen thinks ErdÃ¶s is wrong: we do know why math is beautiful. Joshua Bowman in another thread shared his answer.

Paula's 4th: Rotate things!

This month included NCTM National and that generated some amazing content.

Tina Cardone on learning the language of math.

Mark Chubb hits all the big ideas as he's putting together an assessment workshop.

Sara Van Der Werf also going comprehensive, on engaging students. Her metaphors are always to die for; Ticket to Ride here.

Laila Nur with a hilarious, dynamic, poetic, challenging Ignite: Stay in Your Lane.

Annie Perkins writes about Danny Martin's Iris M. Carl Equity Address, and so does Wendy Menard. Watch it here, Taking a Knee in Mathematics Education. Discuss with us on Twitter afterward.

Paula's 5th: her favorite, origami pocket books. "my personal favorite to do with everyone because you can talk about squares, rotation, triangles, scaling triangles,(third step) pentagons, and then slide 2 pockets them together to make hexagon (so 5 + 5 becomes 5 + 5 -4= 6, very cool), and arrange into non-regular octagon."

Renamed from this excellence to Tennissine. Sigh. |

In this month, the world's oldest human passed away, at 117 years of age. Tajima Nabi was believed to be the last person born in the 19th century. Rest in peace.