Welcome to the
Math Teachers At Play
blog carnival — it's not just for math teachers!
If you like to learn new things and play around with ideas, you're sure to find something intriguing here. Don’t try to read all 40(!) posts at once; take the time to enjoy browsing. Savor a few posts today, and then come back for another helping tomorrow or next week.
At my fortieth birthday party, I got a few of those gag presents meant to remind me how terribly old I was getting.
Math Teachers at Play is less than 40 months old (it used to come out twice a month), but just imagine how many great math posts have been included over the months, in all 40 issues.
Forty: A Puzzle
In English, the number forty is spelled out so that the letters appear in alphabetical order. Can you find any other numbers that work this way, or is forty the only one? (If I couldn't find another, how would I prove it was the only one?) Does switching to another language help?

from You Can Count on Monsters 
40's Trivia
 Forty is a pentagonal pyramidal number.
 Forty is the atomic number of zirconium.
 Negative forty is the one temperature at which the Fahrenheit and Celsius scales correspond; that is, −40°F = −40°C.
 Forty is the number of thieves in Ali Baba and the Forty Thieves, from the Thousand and One Nights. (Both the numbers 40 and 1001 may have meant "many", rather than indicating a specific number.)
 40 = 11000 (base two) = 1111 (base three) = 2*2*2*5
 Forty winks is a nice afternoon nap on a hot summer day.
 40 acres and a mule refers to the shortlived policy, during the last stages of the American Civil War in 1865, of providing arable land to black former slaves who had become free as a result of the advance of the Union armies into the territory previously controlled by the Confederacy, instituted by General Sherman. After the assassination of President Abraham Lincoln, his successor, Andrew Johnson, revoked Sherman's Orders and returned the land to its previous white owners. Because of this, the phrase "40 acres and a mule" has come to represent the failure of Reconstruction policies to return to African Americans the fruits of their labor. (Wikipedia)
 And last but not least, we have the forty hour work week, brought to you by unions.
Early Concepts
Nikki Olivier shares some of her family's
math moments.
Jennifer Knopf brings us
4th of July Fun for beginning counters, with a sorting mat and graph to go with red, white, and blue star marshmallows.
In
How to Teach Math Concepts at the Dinner Table,
Bon Crowder looks through her young daughter's eyes at the commutative and associative properties, along with substitution. These concepts help form a strong foundation for first arithmetic and then algebra.
Arithmetic
Denise Gaskins is
giving away a complete set of the Arithmetic Village picture books, by Kimberly Moore. The stories look beautiful and whimsical. They remind me of the Waldorf arithmetic stories, which are usually shared orally. I'm excited to see these stories in print. (The giveaway is open until July 17. Go comment now at Denise's blog if you're interested.)
Karyn Tripp has created an
addition bingo game, and posted it at her blog.
Maria Miller suggests helping kids focus on the first step of a problem (and then the next) by
bubbling it.
Jennifer Bardsley describes how using coupons to buy toothpaste can turn into a wonderful math lesson for young children in
Coupons and Kids, Math in Action.
In
Math or Magic?,
David Ginsburg asks us to make sure students don't learn math as if it were magic, and walks us through an example involving multiplying fractions.
Rebecca Hanson offers a very simple
arithmetic exercise that gets students thinking more deeply.
The Art in Math
Jenny got her first graders playing with
Turtle Art (a simple programming environment that produces beautiful results), and they loved it. The turtle art software is free to download. To the left you see a 40sided star, and to the right, my first art attempt in TurtleArt. (I loved making it.)
Luyi shows off her friend
Justin's fabulous knot drawings.
Dan MacKinnon gives an example of what you can do with
specialized graph paper, and links to a source for lots of free varieties of it.
Computers
If you haven't been following
toomai's series on building a computer from first principles (using paper and then wood to create adders), you are missing out!
Here's his first post in the series.
Algebra
John Golden has another cool game, called
Linear War. I think of Algebra I as twothirds linear and onethird quadratic; here's John's
quadratic post.
Henri Picciotto writes about
kinesthetic activities for secondary math; I'm looking forward to using some of these in class. (Henri maintains a math ed page as a website rather than a blog. There's lots of good material here; check it out.)
Probability
What's more likely, getting struck by lightning, or hit by a car? Which risky activities do you avoid, and which do you engage in? Take the
BBC's Big Risk Test to learn more about your risktaking profile.
Puzzles and Games
Check out
Dan MacKinnon's Knight's Tour and
King's Tour puzzle posts.
Jim Wilder brings us a
magic square post.
Rachel Lynette offers a symmetry game called
Guess My Grid, with a free game board available.
Teaching and Learning
Denise Gaskins is collecting
quotes from bloggers. Which is your favorite?
Alexandre Borovik blogs about
place value and the problem with not having a name for a number that has just one nonzero digit (which may be followed by any number of zeros).
Alexander Bogomolny blogs about
the ambiguity of math words in English.
Geoff blogs about some
benefits he saw with ProblemBased Learning.
Whit Ford blogs about
Eight Attributes of Effective Activities, Problems, or Projects.
Terrance Banks used a menu system to allow students some say about how their quizzes were graded. He shows us how it works in this blog post.
Allison Cuttler posts about
solving a hard problem and the lessons she took from that about how students feel about problem solving.
I went to a workshop on
Complex Instruction, which involves using groups in math class, and blogged about it.
The Real World
Virtual Math Tutor blogs about
Pyramid Schemes, with math coming to the rescue. I found this post surprisingly timely as I had just received a chain letter in the mail. (Chain letters are illegal in the U.S., so I tried to report it, but haven't succeeded yet.)
Jonah Lehrer blogs about
the problem with math, in sports. "Because it translates sports into a list of statistics, this tool can also lead coaches and executives to neglect those variables that can't be quantified." The problem Jonah describes shows up in lots of other arenas (standardized tests getting you down, anyone?)  I'd love to see more bloggers write about this issue.
John Cook thinks about how different people would answer the
interview question "What's the square root of 101?"
Plus Magazine has an article on the
Unplanned Impact of Maths.
Summer Travels
Ihor found
this sign in Italy, and wonders if numbering the floors this way makes for better math students.
Peter Price looks at Roman ruins to help him teach Roman numeration.
Katie Sorene brings us 7 more buildings of mathematical interest. I wish the math were explained more clearly  I'm not sure I believe all the hype about particular ratios. I'd really like to see a floor plan of the Rushton Triangular Lodge; maybe I'll draw one myself...
Math Poetry
John Cook has posted a
sweet collection of limericks. And Mad Kane offered up her
limerick ode to Tau Day on June 28th (6.28).
Math Haiku for you, from
Yan Kow Cheong.
JoAnne Growney posts math poetry regularly. In
this poem, Robert Gerther asks whether math truly is a universal language.
Visit Our Sister Carnivals
Exit the Carnival Here
And that rounds up this edition of the
Math Teachers at Play blog carnival. I hope you enjoyed the ride. The next installment of our carnival will open on August 19 at
I Hope This Old Train Breaks Down. If you would like to contribute, please use this
handy submission form or
email Mimi directly. (We've had trouble with the submission form these past few months. We hope they’ll get it fixed.) Posts must be relevant to students or teachers of preK12 mathematics. Old posts are welcome, as long as they haven’t been published in past editions of this carnival. Past posts and future hosts can be found on our
blog carnival index page.