Math Teachers at Play #58

No 58 - gold on blue[Feature photo (above) by Alex Kehr. Photo (right) by kirstyhall via flickr.]

Welcome to the Math Teachers At Play blog carnival — a smorgasbord of ideas for learning, teaching, and playing around with math from preschool to pre-college. If you like to learn new things and play around with ideas, you are sure to find something of interest.

Let the mathematical fun begin…


By tradition, we start the carnival with a pair of puzzles in honor of our 58th edition. Click to download the pdf:

How CRAZY Can You Make It


A Smith number is an integer the sum of whose digits is equal to the sum of the digits in its prime factorization.

Got that? Well, 58 will help us to get a better grasp on that definition. Observe:

58 = 2 × 29


5 + 8 = 13
2 + 2 + 9 = 13

And that’s all there is to it! I suppose we might say that 58’s last name is Smith. [Nah! Better not.]

  • What is the only Smith number that’s less than 10?
  • There are four more two-digit Smith numbers. Can you find them?

And now, on to the main attraction: the blog posts. Many articles were submitted by their authors; others were drawn from the immense backlog in my Google Reader. Enjoy!


Subitizing.svg[Image © Nevit Dilmen.]

Teacher: If you had 5 apples in one hand and 7 apples in other hand, what would you have?

Student: Very large hands!

Teacher: If I had 5 coconuts, and then I gave you 3 of them, how many coconuts would I have left?

Student: I don’t know.

Teacher: Why not?

Student: Because all of our practice problems were about apples!

  • The Relentlessly Fun, Deceptively Educational Mom tells how to make and measure snowflakes in It’s Snowing Angles!
  • Yelena says, “Like so many other kids, my son loves listening to stories. So I try to find or make up stories of mathematical adventures for him. This particular one, about two lonely Moebius Ants, was inspired by Vi Hart’s video Wind and Mr Ug.”


Baumdiagramm_Urnenziehung[Image by kaʁstn Disk/Cat.]

Q: Why was 1/5 sent to a counselor?

A: Because he was two-tenths.

(noun) an illegal mathematical move when working with rational numbers, such as dividing by 0 or assuming that a/b + c/d = (a + b)/(c + d)

  • The Piwi Kids’ Mom says, “It is hard for any Mama to watch their child struggle with something. The ‘I hate Math’ comment still happens but we hear it less.” She explains how in What works for us…Math.
  • Alicia shares 22 Fun ways to help kids learn their math facts.”Remember that some kids naturally memorize math facts much easier than others. Kids who are right brained learners are often ‘late’ in memorizing math facts but are capable of doing very advanced math despite it. Don’t obsess over the fact that your kids don’t know it all by heart, and don’t wait to get into higher math until they know it all by heart.”
  • Julie created the skip-counting game Speed! to help her homeschooled daughter learn multiplication. Now she’s excited that Speed! is in the iPad App Store.
  • Middle- to upper-elementary students love to collect facts about their friends, books, pets, or whatever else catches their interest. Heather offers advice on sharing that data in How to Make a Good Graph.
  • For my contribution to this month’s carnival, I challenge your children to join us in the 2013 Mathematics Game, an arithmetic puzzle for all ages. Elementary students can start with the numbers 1-20, middle school 1-50, and high school students can take on the full 1-100.


Equation_illustration_subtraction.svg[Image by Maschen.]

Student: In the expression x3, what do you call the 3?

Teacher: An exponent.

Teacher: In the expression y2, what do you call the 2?

Student: A y‑ponent.

  • Jena’s students finished their first quarter on coordinate plane geometry, and now they’re dreaming of vacations in Geometry Project.
  • Drafting can be a great way to learn the basics of geometry. Check out Julie’s daughter’s creations in Math Art – Geometry.


Supercalc[Image by Timboliu.]

After a logic exam…

Student: “Sir, did I pass or fail the exam?”

Professor: “Yes.”

  • Sue has to teach Centroid (Center of Mass) to her calculus students. She says, “The textbook explanation is inadequate, and I found nothing good online. So I wrote my own explanation. I now understand it better than I ever did before. (Not surprising, huh? If you’re a student, this is an important principle of learning. After you think you understand something, try to write an explanation of it and see how much deeper your understanding can get.)”


Pentomino_Puzzle_Solution_8x8_Minus_Center.svg[Image by Rob Zako.]

Take a positive integer n.
No, wait; n is too large.
Take a positive integer k …


635px-Math5[Image by Proferichardperez.]

The cannibal family was eating dinner. One son says, “I really hate my math teacher.”

The other son says, “I know. He’s so tough!”

The mother tells them, “Quit complaining. If you don’t like the meat, just eat the noodles.”



The Smith numbers puzzle is from Terry Trotter at Trotter Math, and the other quotations are from Patrick Vennebush at his Math Jokes 4 Mathy Folks blog.

Math diagrams are courtesy of Wikimedia Commons: Mathematics, except for the book image, which is from (where I receive a small commission through Skimlinks if you actually click through and buy it no longer, thanks Illinois!).

And that rounds up this edition of the Math Teachers at Play carnival. I hope you enjoyed the ride.

The next installment of our carnival will open sometime during the week of February 11-15 at Learners in Bloom. If you would like to contribute, please use this handy submission form. Posts must be relevant to students or teachers of preK-12 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 information page.

We need more volunteers. Classroom teachers, homeschoolers, unschoolers, or anyone who likes to play around with math (even if the only person you “teach” is yourself) — if you would like to take a turn hosting the Math Teachers at Play blog carnival, please speak up!

9 thoughts on “Math Teachers at Play #58

  1. Thank you, Denise, for finding my post and sharing it. As always, you did an outstanding job and I know that your labor of love is deeply appreciated by our community.
    Dave Marain

  2. Denise, thank you so much for hosting this carnival and featuring Moebius Noodles games! I’ve been reading other submissions – so many wonderful ideas and excellent resources. Thank you for bringing it all together.

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