Puzzle: Exploding Dots

I’m planning ahead for my fall semester homeschool co-op math class. Definitely going to try this with the kids…

Encourage your children to have some fun this week with this Exploding Dots math puzzle from The Global Math Project. What do they notice? Does it make them wonder?

More Explosive Math

You may recognize the connection between Exploding Dots and binary numbers. Or not — the puzzle is accessible to people at all ages and levels of mathematical sophistication.

But what I find amazing is that this puzzle can help us understand all sorts of topics in elementary arithmetic and algebra. So cool!

If you’d like to investigate Exploding Dots in depth, check out James Tanton’s free G’Day Math online course.

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FAQ: Trouble Finding the Right Math Program

“I can’t find a home school math program my son likes. We’ve tried Singapore Math, Right Start, Saxon, and Math Mammoth. We subscribed to a month of IXL Math to keep him in practice, but he hates that, too. I know I shouldn’t have changed so many times, but this was our first year of homeschooling, and I was trying to please him. But I’m running out of things to try. Do you think Life of Fred might work?”


You’ve tried all those math programs in one year? Many people recommend that new homeschoolers take a few months off to “detox” from the classroom setting, to relax and enjoy the freedom of making their own choices. But your son might want a few months to detox from his homeschool experience.

I suggest you set aside all those books and focus on games and informal math. Try to avoid schoolish lessons until your son starts to enjoy learning for its own sake. The Internet offers an abundance of creative math ideas.

  • For example, download the Wuzzit Trouble or DragonBox apps to play with, but don’t make it a homework assignment.
  • Or let him choose one of the activities at Gordon Hamilton’s Math Pickle website and explore it for a day or a week or as long as it remains interesting.
  • Browse through the Primary Level 1 or Level 2 puzzles and games at the Nrich Mathematics website for more ideas.

Look for more playful math on my blog’s resource pages:

Explore Big Concepts: Infinity

Math that captures a child’s imagination can make the more tedious work seem bearable. For instance, in the 1920s, mathematician David Hilbert created a story about an imaginary grand hotel with an infinite number of rooms.

Explore Big Concepts: Fractals

Sierpinski-tortillasTake a mental trip to infinity by playing with fractals. Cynthia Lanius’s online Fractals Unit for Elementary and Middle School Students offers a child-friendly starting point.

Fractals are self-similar, which means that subsections of the object look like smaller versions of the whole thing.

Most children enjoy exploring the concept of infinity with hands-on fractal patterns, such as this Sierpinski triangle made of tortilla chips. Talk about what you notice and wonder: How does the triangle grow? How many chips will we need for the next stage?

The Daily Four

If you worry that your son needs to keep practicing traditional arithmetic during his break, try making him a series of Daily Four pages:

  • Fold a sheet of plain paper in half both ways, making four quarter sections.
  • Write one math problem in each part. Choose them from any of your math books.
  • Make sure each problem is different — one addition, one fractions, one multiplication, or whatever — and that none of them are hard enough to cause frustration.
  • Don’t worry about an answer sheet. Show him how to use a calculator to check his work.

You can make up a whole week’s worth of these problem sheets at once, with a balanced mix of problems for each day. Your son won’t feel overwhelmed, but you’ll know he’s reviewing his number skills.

Or download some of the Corbettmaths 5-a-Day practice sheets for him. Some problems may seem too easy while others require concepts he hasn’t studied yet. Easy review won’t hurt anything, but do let him skip the problems that feel too hard.


Credits: “Rock Surfer Boy” by Ken Bosma and “Boy” by Isengardt via Flickr. (CC BY 2.0) Hotel Infinity video by Tova Brown.

Click for details about Let's Play Math bookThis post is an excerpt from my book Let’s Play Math: How Families Can Learn Math Together—and Enjoy It, as are many of the articles in my Let’s Play Math FAQ series.

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Playful Math Carnival #100 via Three J’s Learning

Check out the new carnival of playful math for all ages at Three J’s Learning blog. You’re sure to enjoy this great collection of puzzles, math conversations, crafts, teaching tips, and all sorts of mathy fun.

Wow, the 100th Math Teachers at Play! Such an honor to put together this milestone edition.

I asked the 3J’s for observations and facts about 100:

  • It is written with a 1 and two 0s
  • Square number (10 x 10)
  • It is a sum of two squares 64 + 36

Click here to go read the carnival blog!

It’s so cool to see carnival number 100. Thank you to ALL the hosts and to everyone who has participated over the years!

Past carnivals are still full of mathy treasure. Check them out:

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Ebook Sale at Smashwords

If you read ebooks, check out this great sale at Smashwords. Through the end of July, all of my playful math ebooks are 25% off — and my daughter’s novel Banished (The Riddled Stone, Book One) is free!

Just remember to enter the discount code (SFREE for Banished, and SSW25 for all the others) at checkout.

Click an image below to read more about that book. The discount codes are also listed on each book’s description page.

LetsPlayMathPPBcover CountingGames AdditionGames MYCPcover Banished-600 Hunted-600

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Review: Math & Magic in Wonderland

Are you looking for a fun book to read over the summer? I just finished Lilac Mohr’s delightful Math & Magic in Wonderland, and I loved it.

Highly recommended, for kids or adults!

About the Book

Math-Magic-WonderlandA Jubjub bird disguised as a lark,
Borogroves concealing a snark,
When you’re in Tulgey Wood, you must
Be careful whom it is you trust…

With the discovery of Mrs. Magpie’s Manual of Magic for Mathematical Minds, Lulu and Elizabeth embark on an exciting journey to a realm inspired by Lewis Carroll’s poetry. The twins must use ingenuity and sagacity to solve classic logic puzzles that promise to uncover the book’s secrets and earn them The Vorpal Blade. In this interactive novel, the reader is invited to play along with the two heroines on their grand mathematical adventure.

Do you have the smarts to help Lulu and Elizabeth outwit the frumious Bandersnatch?

It’s time to enter Wonderland and find out!

–from the back cover of Math & Magic in Wonderland by Lilac Mohr

What I Liked

Puns, poetry, and plenty of puzzles. Tangrams, tessellations, truth-tellers and liars. History tidbits and many classics of recreational mathematics.

The sisters Lulu and Elizabeth seem real — though perhaps more widely read than most of us. They are different from each other. They make mistakes and have disagreements. But they never deteriorate into the cliché of sibling rivalry that passes for characterization in too many children’s books.

In each chapter, the girls must solve a language, math, or logic puzzle to proceed along their journey. Then a “Play Along” section offers related puzzles for the reader to try.

No matter how challenging the topic, the book never talks down to the reader.

What I Didn’t Like

… Um … Honestly, I can’t think of anything.

Since it’s traditional to criticize the editing of self-published books, I will say this: There was at least one place where the wording seemed a bit awkward. I would have phrased the sentence differently. But don’t ask me to identify the page — I was too caught up in the story to bother jotting down such a quibble. And I tried flipping through the book as I wrote this post, but I can’t find it again.

Buy, or Don’t Buy?

Buy. Definitely buy.

Unless you hate logic puzzles and despise Lewis Carroll’s poetry.

But for everyone else, this book is truly a gem. If you like The Cat in Numberland or The Man Who Counted, then I’m sure you’ll enjoy Math & Magic in Wonderland.

Useful Links

Disclaimer: Like almost all book links on my blog, the links in this post take you to Amazon.com, where you can read descriptions and reviews. I make a few cent’s worth of affiliate commission if you make a purchase — but nowhere near enough to influence my opinion about the book.

And Now for the Giveaway

Math-Magic-WonderlandLilac offered a paperback copy of Math & Magic in Wonderland for one lucky reader of Let’s Play Math blog.

The giveaway is done. Congratulations, Keshua!

But the comments section below remains open, and I’d still love to hear your answers:

  • Tell us about your favorite language, math, or logic puzzle book! Or share a book you’ve been wanting to read.

Playful Math Carnival #99 via Eat Play Math Blog

mtap99Check out the new playful math education carnival at eat play math blog. Math art, tessellations, review games, problem-solving challenges, and all sorts of mathy fun. Not to mention, Raspberry Tiramisu!

Welcome to the Math Teachers at Play #99 Blog Carnival, a monthly smorgasbord of links to bloggers all around the internet who have great ideas for learning, teaching, and playing around with math…
Click here to go read the carnival blog!

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10 Ways to Celebrate World Tessellation Day

Guest post by Emily Grosvenor.

June 17 marks the first-ever World Tessellation Day, a holiday I created to bring awareness to the fun of finding and making tessellations.

Will you celebrate with us?

Here are 10 great ways to play with tessellations, learn about them, and introduce your children to a math concept that opens a variety of creative learning opportunities.

1) Learn about tessellations with your kids.

A tessellation is a tiled mosaic pattern of the same shape laid out over and over again, repeating into infinity. Tessellations can be found in nature, or they can be created by people. Learn more at these websites:

1WorldTessellationDayExcept where otherwise noted, graphics and photos copyright ©2016 Emily Grosvenor. All rights reserved.

Continue reading 10 Ways to Celebrate World Tessellation Day