## Math Game Monday: Sam Vandervelde’s Criss-Cross

This game offers students a chance to practice mathematical reasoning (and possibly notice a connection to the Euler characteristic).

“Sam Vandervelde’s Criss-Cross” is an excerpt from 312 Things To Do with a Math Journal, available as an ebook at my bookstore (Thank you for cutting out the middleman!) and in ebook or paperback through many online retailers. Read more about my playful math books here.

The Math Game Monday posts will be available for one week only. If you missed this one, explore the Topic Tag links in the sidebar. There are more than forty free games scattered around the blog. Have fun playing math with your kids!

## The Colors-of-Fall Carnival: Playful Math #160

Welcome to the 160th edition of the Playful Math Education Blog Carnival — a smorgasbord of delectable tidbits of mathy fun. It’s like a free online magazine devoted to learning, teaching, and playing around with math from preschool to high school.

Bookmark this post, so you can take your time browsing.

There’s so much playful math to enjoy!

By tradition, we start the carnival with a puzzle/activity in honor of our 160th edition. But if you’d rather jump straight to our featured blog posts, click here to see the Table of Contents.

## Try This Puzzle/Activity

Appropriately for an October carnival, 160 is an evil number.

A number is evil if it has an even number of ones in binary form. Can you find the binary version of 160? (Hint: Exploding Dots.)

160 is also a polyiamond number. If you connect 9 equilateral triangles side-to-side, a complete set of 9-iamond shapes would have 160 pieces.

But sets that large can be overwhelming. Try playing with smaller sets of polyiamonds. Download some triangle-dot graph paper and see how many different polyiamond shapes you can make.

What do you notice? Does it make you wonder?

What designs can you create with your polyiamonds?

Photo by Daiga Ellaby on Unsplash

## Math Game Monday: Collect Ten

This preschool game builds counting and subitizing skills. (Subitizing means recognizing at a glance how many objects are in a group.)

“Collect Ten” is an excerpt from Counting & Number Bonds: Math Games for Early Learners, available as an ebook at my bookstore (Thank you for cutting out the middleman!) and in ebook or paperback through many online retailers. Read more about my playful math books here.

The Math Game Monday posts will be available for one week only. If you missed this one, explore the Topic Tag links in the sidebar. There are more than forty free games scattered around the blog. Have fun playing math with your kids!

## Math Game Monday: Ultimate Multiple-Tac-Toe

This game gives players lots of practice with their multiplication facts while strategically blocking their opponents.

“Ultimate Multiple-Tac-Toe” is free on this website for one week only. It’s an excerpt from Multiplication & Fractions: Math Games for Tough Topics, available as an ebook at my bookstore (Thank you for cutting out the middleman!) and in ebook or paperback through many online retailers. Read more about my playful math books here.

The Math Game Monday posts will be available for one week only. If you missed this one, explore the Topic Tag links in the sidebar. There are more than forty free games scattered around the blog. Have fun playing math with your kids!

## Don’t Miss Playful Math Carnivals #158 and #159!

Here is SOOOOO MUCH GREAT MATH!

Each monthly carnival brings you a new collection of ideas for playing math from preschool to high school. It’s like a free online magazine of mathematical adventures, helpful and inspiring no matter when you read them.

Alexa Kapor-Mater put together an awesome carnival, with fun facts, activity ideas, puzzles, videos, problem-solving tips, and interesting stuff you should know. Wow!

John Golden found a delightful assortment of playful tidbits from around the internet, fun songs, games, activities, puzzles, math art, and the #Mathober challenge prompts. Love it!

### Help Us Keep the Carnival Going

The Playful Math Blog Carnival is a joint effort. We depend on our volunteer hosts to collect blog posts and write the carnival each month.

Putting together a blog carnival can be a lot of work, but it’s a great opportunity to share the work of bloggers you admire and to discover new math-friends online. Classroom teachers, homeschoolers, college professors, unschoolers, or anyone who likes to play around with math — if you would like to take a turn hosting the carnival, please speak up.

Check the details on the carnival’s home page, and then leave a comment here on the blog or email me directly to let me know when you want to host.

CREDITS: Feature photo (top) by Count Chris on Unsplash.com.

## Math Game Monday: Two-Digit Number Train

This game makes players think about place value and probability as they race to complete their number train.

“Two-Digit Number Train” is an excerpt from Math You Can Play Combo: Number Games for Young Learners, available as an ebook at my bookstore (Thank you for cutting out the middleman!) and in ebook or paperback through many online retailers. Read more about my playful math books here.

The Math Game Monday posts will be available for one week only. If you missed this one, explore the Topic Tag links in the sidebar. There are more than forty free games scattered around the blog. Have fun playing math with your kids!

## Math Game Monday: Operations

This game offers students in upper-elementary and beyond plenty of practice with mental math and the order of operations.

“Operations” is an excerpt from Prealgebra & Geometry: Math Games for Middle School, available as an ebook at my bookstore (Thank you for cutting out the middleman!) and in ebook or paperback through many online retailers. Read more about my playful math books here.

The Math Game Monday posts will be available for one week only. If you missed this one, explore the Topic Tag links in the sidebar. There are more than forty free games scattered around the blog. Have fun playing math with your kids!