Prealgebra & Geometry Games Now Available

Publication Day!

Prealgebra & Geometry: Math Games for Middle School hits the online bookstores today.

Check Your Favorite Store

You can prepare your children for high school math by playing with positive and negative integers, number properties, mixed operations, algebraic functions, coordinate geometry, and more. Prealgebra & Geometry features 41 kid-tested games, offering a variety of challenges for students in 4–9th grades and beyond.

A true understanding of mathematics requires more than the ability to memorize procedures. This book helps your children learn to think mathematically, giving them a strong foundation for future learning.

And don’t worry if you’ve forgotten all the math you learned in school. I’ve included plenty of definitions and explanations throughout the book. It’s like having a painless math refresher course as you play.

Continue reading Prealgebra & Geometry Games Now Available

Math Puzzle from the Ancient Kingdom of Cats

It may look like Cimorene has lain down on the job, but don’t be fooled! She’s hard at work, creating a math investigation for your students to explore.

Cats know how important it can be for students to experiment with math and try new things. Playing with ideas is how kittens (and humans!) learn.

Cimorene wants you to know that the Make 100 Math Rebels Kickstarter offers a great way for human children to learn math through play. She encourages you to go watch the video and read all about the project.

Too often, school math can seem stiff and rigid. To children, it can feel like “Do what I say, whether it makes sense or not.” But cats know that kids are like kittens — they can make sense of ideas just fine if we give them time to play around.

So Cimorene says you should download the free sample journaling pages from the Math Rebels Kickstarter page. The beautiful parchment design makes doing math an adventure.

[The free download will always be there, even after the Kickstarter project ends.]
Make 100 Math Rebels Kickstarter

Cimorene’s Puzzle Challenge

Cimorene’s math puzzle is a classic geometry problem from the ancient Kingdom of Cats: Squaring the Circle.

Draw a circle on your journal page. Can you draw a square (or rectangle) that has the same area?

How would you even begin such a task?

Notice Cimorene’s hint in the photo above: Try drawing the square that just touches the edges of your circle. (We call those just-touching lines “tangents” to the circle.)

  • What do you notice? Do the square and the circle have the same area? How close are they?

The tangent square sets an upper limit on the area of the circle. You can see that any square that exactly matches the circle would have to be smaller than the tangent square.

  • Can you find a square that sets a lower limit on the area of the circle? That is, a square that must have less area than the circle?
  • What’s the biggest square you can draw inside your circle? Can you find a square that has all four corners on the circle?

We call that biggest-inside square “inscribed” in the circle. Any polygon whose corners all sit on the circle is an inscribed polygon.

  • Play around with circles and squares. How close can you get to matching their size?

Further Exploration

After you have explored for awhile on your own, Cimorene has one more twist in her puzzle.

In the ancient Kingdom of Cats, the wise ones estimated the area of a circle this way:

Divide the width of the circle in thirds, and then in thirds again. (That is, cut the diameter into nine parts.) Draw a square with sides measured by eight such parts.

You can try this on your journaling page by drawing a circle that is nine squares wide. Then draw a square overlapping it, with sides that are eight squares in length.

  • How closely do the areas match?

Playing with Pi

Here’s a surprise: Cimorene’s puzzle isn’t really about squares, but about calculus.

The problem of Squaring the Circle is really a much bigger question: Finding the area of a square, rectangle, or other polygon is relatively easy, but how can we discover the area of a curved shape?

For a circle, the area is related to the number pi, which is the number of times you would have to walk across the circle to equal the distance of one time walking around it.

graphic by John Reid (cc by-sa 3.0)

graphic by John Reid (cc by-sa 3.0)
So the problem of Squaring the Circle is really the same as asking, “What is the value of pi?”

  • Can you figure out what approximate value for pi matches the 8/9 square used in the ancient Kingdom of Cats?

If you’d like to learn more about pi, get ready for a celebration: Pi Day is coming soon! Every year, millions of children celebrate math on March 14th, because if you write the date as 3/14, it’s the same as the first three digits of pi.

Find out more about playing with pi in my Pi Day Round-Up post.

You may also enjoy:

Share Your Stories

Cimorene would love to hear about your children’s experiences playing with math! Please share your story in the comments below.

New Printable Puzzle Books: Diffy Inception

The best way to practice math is to play with it—to use the patterns and connections between math concepts in your pursuit of something fun or beautiful.

Diffy Inception puzzles have their own symmetric beauty, but mostly they are just plain fun. Students can practice subtraction and look for patterns in the difference layers.

I just published four new activity books to our online store:

Notes to the teacher include puzzle instructions, game variations, journaling prompts, and more. Plus answers for all puzzles.

Available with 8 1/2 by 11 (letter size) or A4 pages.

Click for a Preview

My publishing company runs this online store, so you can find all my playful math books there — including an exclusive pre-publication ebook edition of my newest title, Prealgebra & Geometry: Math Games for Middle School. Click here to browse the Tabletop Academy Press store.

FAQ: Playful Math for Older Students

My students are so busy that time-consuming math projects are a luxury. How is it possible for older kids to play with mathematics?

Too often, the modern American school math curriculum is a relentless treadmill driving students toward calculus. (Does this happen in other countries, too?)

But that’s definitely not the only way to learn. For most students, it’s not the best way, either.

Here are a few ideas to get your older children playing with math…

Continue reading FAQ: Playful Math for Older Students

More Math War with Special Decks

Just updated my blog post Math Game: War with Special Decks to add a couple of games I missed the first time around:


If you’d like more ways to play with math from preschool to high school, check out My Favorite Math Games.

CREDITS: “Red playing cards” photo by José Pablo Iglesias via

Prealgebra & Geometry Preorders

My book Prealgebra & Geometry: Math Games for Middle School is scheduled for release to regular bookstores in February, 2021. Because no publisher wants to send a new book into the world during such hectic, unsettled times as a big election, the winter holidays, or during inauguration season.

But preorder links are beginning to appear at several of the major online booksellers. And more stores will join them, as the information filters through their website systems.

The paperback will also be up for preorder, whenever the sites catch that update.

And remember: If you don’t favor a particular bookstore, you can buy the early-release ebook right now at my publisher’s webstore — and get a 10% discount if you order before 15 October.

Math Game: Hit Me

I believe this was the first math game I ever invented. Of course, ideas are common currency, so I’m sure other math teachers thought of it before I did. But to me, it was original.

I’ve blogged about the game before, but here’s the updated version as it appears in my new book Prealgebra & Geometry: Math Games for Middle School — scheduled for publication in early 2021. Sign up for my newsletter to get updates.

Hit Me

Math Concepts: integer addition, absolute value.

Players: two or more.

Equipment: playing cards (two decks may be needed for a large group).

Continue reading Math Game: Hit Me

Math Game: War with Special Decks

The all-time most-visited page on this site is my post about Math War: The Game That Is Worth 1,000 Worksheets. It’s easy to adapt to almost any math topic, simple to learn, and quick to play. My homeschool co-op students love it.

But Math War isn’t just for elementary kids. Several teachers have shared special card decks to help middle and high school students practice math by playing games.

Take a look at the links below for games from prealgebra to high school trig. And try the Math War Trumps variation at the end of the post to boost your children’s strategic-thinking potential.

Have fun playing math with your kids!

Continue reading Math Game: War with Special Decks

Math for Star Wars Day

May the Fourth be with you!

Here is a math problem in honor of one of our family’s favorite movies…

Han Solo was doing much-needed maintenance on the Millennium Falcon. He spent 3/5 of his money upgrading the hyperspace motivator. He spent 3/4 of the remainder to install a new blaster cannon. If he spent 450 credits altogether, how much money did he have left?

Stop and think about how you would solve it before reading further.

Continue reading Math for Star Wars Day

A Puzzle for Palindromes

If you haven’t seen the meme going around, this is a palindrome week because the dates (written American style and with the year shortened to ’19) are the same when reversed.

Here’s a math puzzle for palindrome week — or any time you want to play with math:

  • Print a 100 chart.
  • Choose a color code.
  • Play!

What do you think: Will all numbers eventually turn into palindromes?


You can find all sorts of hundred charts on my Free Math Printable Files page.

Read about the history of palindromes on Nrich Math’s Palindromes page.

Find out more about the Palindromic Number Conjecture in Mark Chubb’s article An Unsolved Problem your Students Should Attempt.

Or play with Manan Shah’s advanced palindromic number questions.