A Beautiful Puzzle

This lovely puzzle (for upper-elementary and beyond) is from Nikolay Bogdanov-Belsky’s 1895 painting “Mental Calculation. In Public School of S. A. Rachinsky.” Pat Ballew posted it on his blog On This Day in Math, in honor of the 365th day of the year.

I love the expressions on the boys’ faces. So many different ways to manifest hard thinking!

Here’s the question:

No calculator allowed. But you can talk it over with a friend, as the boys on the right are doing.

You can even use scratch paper, if you like.

Thinking About Square Numbers

And if you’d like a hint, you can figure out square numbers using this trick. Think of a square number made from rows of pennies.

Can you see how to make the next-bigger square?

Any square number, plus one more row and one more column, plus a penny for the corner, makes the next-bigger square.

So if you know that ten squared is one hundred, then:

… and so onward to your answer. If the Russian schoolboys could figure it out, then you can, too!

Update

Simon Gregg (@Simon_Gregg) added this wonderful related puzzle for the new year:

Check Out These Cool Math Sales

I’ve been following Sonya’s Arithmophobia No More blog for a couple of years, and I love the work she is doing. But this month, she’s teamed up with Lacy at Play, Discover, Learn (another great blog to follow!) to offer a humongous bundle of playful math.

You get math journaling pages, games, creative task cards, thought-provoking worksheets, and video training resources to help you build your child’s understanding of math from arithmetic to early algebra. Wow!

These activities are perfect for homeschooling families or anyone looking to supplement their child’s current math curriculum with effective discovery-based activities. If you’ve ever wondered what to do with those Cuisenaire rods you picked up on sale way back when, this bundle is for you.

I’m so looking forward to using some of these ideas with my elementary homeschool co-op kids next year!

Sale price is $30 from December 2-15.

Cuisenaire Rod Activities Blowout Bundle

But Wait, There’s More

If you’ve been reading my blog for very long, you’ve probably seen how much I love the blog, books, and classes available from the Natural Math folks.

Their newest book is just off the presses — Funville Adventures, a math adventure chapter book.

And until December 20, they’re having a holiday sale. Make your own bundle of any Natural Math books. Playful algebra, calculus for 5-year-olds, inquiry problems and more: Great deal!

Natural Math Book Sale

Stock Up on My Playful Math Books

Finally, if you’ve been wanting to pick up a paperback copy of Let’s Play Math or some of my game books, or maybe a set of dot-grid math journals, I’m currently offering a discount on bulk orders.

Bundle ANY assortment of titles. Stock up on books for your family, friends, or homeschool group.

  • 2–4 books: 15% discount off retail prices
  • 5–9 books: 25% discount
  • 10–19 books: 35% discount
  • 20+ books: 35% discount, and free Continental U.S. standard shipping or the equivalent discount off other shipping options

Bulk Order Playful Math Paperbacks

(US customers only: We’re sorry we can’t offer bulk discounts for our international readers, but the complexities of international duties and tax laws are too much for this very small family business.)

Do You Know of Any Math Deals?

Apollonian greetings from my homeschool co-op kids, and best wishes for a grace-filled holiday season.

If you’ve seen a great deal or holiday price on a math resource you love, please share!

Add your deal to the comment section below, so we can all take advantage of the math joy this season.

How to Talk Math With Your Kids

A friend shared this video, and I loved it! From Kent Haines, a father who happens to also be a math teacher…

“I hope that this video helps parents find new ways of interacting with their kids on math topics.”

Kent Haines

More from Kent Haines

Advice and Examples of Talking Math with Kids

Danielson-Talking Math

If you enjoyed Kent’s video, you’ll love Christopher Danielson’s book and blog.

It’s a short book with plenty of great stories, advice, and conversation-starters. While Danielson writes directly to parents, the book will also interest grandparents, aunts & uncles, teachers, and anyone else who wants to help children notice and think about math in daily life.

“You don’t need special skills to do this. If you can read with your kids, then you can talk math with them. You can support and encourage their developing mathematical minds.
 
“You don’t need to love math. You don’t need to have been particularly successful in school mathematics. You just need to notice when your children are being curious about math, and you need some ideas for turning that curiosity into a conversation.
 
“In nearly all circumstances, our conversations grow organically out of our everyday activity. We have not scheduled “talking math time” in our household. Instead, we talk about these things when it seems natural to do so, when the things we are doing (reading books, making lunch, riding in the car, etc) bump up against important mathematical ideas.
 
“The dialogues in this book are intended to open your eyes to these opportunities in your own family’s life.”

— Christopher Danielson
Talking Math with Your Kids

 
* * *

This blog is reader-supported.

If you’d like to help fund the blog on an on-going basis, then please join me on Patreon for mathy inspiration, tips, and an ever-growing archive of printable activities.

If you liked this post, and want to show your one-time appreciation, the place to do that is PayPal: paypal.me/DeniseGaskinsMath. If you go that route, please include your email address in the notes section, so I can say thank you.

Which I am going to say right now. Thank you!

“How to Talk Math With Your Kids” copyright © 2017 by Denise Gaskins. “Kids Talk” photo (top) by Victoria Harjadi via Flickr (CC BY 2.0). “Parent Rules” by Kent Haines.

10 Ways to Play Math with Play-Doh

Today we have a guest post from Lucy Ravitch, author of the new Kickstarter picture book Trouble with Monkeys: A math concept story of place value. She’s sharing a few ideas from her Math Activity Thursday (M.a.Th.) video series. Enjoy!


Hello, math fans and enthusiasts! Each week I try to give you and your family a fun math activity to try. Two months ago I posted this video with ten ways to turn play dough into an engaging activity for lower and upper elementary math.

If you want to make your own dough from scratch here are a few simple recipes. I encourage you to let your children play freely at first, before trying these activities.

Below I have identified some of the math concepts that your kids will experience as they play.

1. Toss It

Practice counting. With older children, record your results and make a graph of the data.

  • How many times can you catch it in a row? What’s your average number of tosses?
  • Talk about attributes. Does the size or color of the play dough balls make a difference?
  • How high are you tossing it? Talk about measuring systems. Do you use feet and inches, or meters and centimeters?
  • If you know how to juggle, time how long you can keep the balls going.

2. Smash It

Make several small balls or pieces. Then play as you smash them.

  • Play a NIM game: Make 10-15 small play dough balls. Take turns. On your turn, you can smash one ball or two. Whoever smashes the last ball wins the game.
  • Or smash your math facts: Choose several equations for your children to practice. Write each answer on a 3×5 card. Lay out each card next to a play dough piece. As you call out the equations, kids smash the play dough next to the correct card.

3. Shape It

Have fun molding your play dough. Roll it out to cut shapes.

  • Try making 3D shapes while practicing your math vocabulary. MathisFun.com has a great section about solid geometry. Can you find three math terms that are new for you?
  • Roll out the dough and cut 2D shapes. Discuss their attributes. Can you cut your shape in half to be symmetrical?

4. Hide Things in It

Find small objects around the house and enclose them inside play dough.

  • Take turns hiding small objects in play dough. Optional: Give a one-minute time limit to guess before opening it. This gives you and your kids a chance to talk about size, shape, or other attributes.
  • Have challenges to use the least amount of dough to hide identical objects. Two players have two minutes to hide an object in as little play dough as possible. The object must be completely concealed within the dough. What methods will you use?

5. Make Imprints on It

Show off your design skills and observe textures.

  • You can practice counting as you poke and press your fingers or objects into the dough. Older children can discuss the distance between impressions and/or the pressure applied.
  • As you and your kids make designs, talk about what you notice: Is your design symmetrical? What tools did you use (toothpicks, pencils, marbles, fingers, toy cars)? Which objects make interesting textures?

6. Cut It

Use a butter knife or the edge of a ruler to cut your play dough. Discuss findings as you play and explore.

  • In the video, I posed the question: how many sections do you get if you make only three cuts? Try it and see.
  • Does the number of pieces change if you use a shape other than a flat circle?
  • Discuss making straight cuts that will intersect or be parallel. Bring in more geometry terms.
  • Experiment with a different number of cuts.

7. Weigh It

Pull out a kitchen scale or balancing scales to use with dough.

  • Older children can make conversions between ounces to grams. They can make calculations about doubling or multiplying the measured weight. With younger kids, try using balancing scales. Compare the weights between pieces.
  • Try making two pieces that weigh exactly the same. This is harder than it sounds! For small children, this gives them the opportunity to see that the mass (weight) of an object can come in different shapes.

8. Measure It

Use a ruler or measuring tape while you play. There are several ways you can measure your dough — height, width, and length.

  • How long can you extend one ounce of dough? Pick your own size/weight of play dough and see who can get the longest. What fraction of a yard or meter is it?
  • Discuss height and what it takes to make dough stand vertically. How tall can you get three ounces to stand? Can anything help make it taller?

9. Roll It

Make sure you have plenty of room for this activity. Playing outside or on smooth floors works best.

  • With one push how far does your play dough roll? Is there an ideal size for a piece? Is there an ideal weight for rolling?
  • Is the ground sloped? What effects does the rolling surface have?
  • Why do some shapes roll easily while others don’t? Can you create a not-round shape that will roll?

10. Compare It

Compare similarities and differences between dough colors and types. Consider comparing the previously listed activities

  • If you made your own dough, compare consistency between batches. Is homemade dough denser or lighter than store-bought dough?
  • What are differences between the dough you played with and the dough that has not been touched?
  • Which of these activities do you think will take the shortest amount of time? The longest? Or put the activities in order based on how much dough you will need — least to greatest.

May you and your students have fun as you play with dough!


About the Author

Lucy blogs at kidsmathteacher.com and is the author/creator of Kids Menu Books. The first book in that series is The Pancake Menu, an interactive book that lets kids practice math as they play restaurant.

And be sure to visit Lucy’s Kickstarter project! She’s teamed up with artist Trav Hanson to create the delightful picture book Trouble with Monkeys: A math concept story of place value.

Playful Math on Kickstarter

Have you noticed that we live in a wonderful era of mathematical innovation? Not only at the “it’s all over my head” level — which is growing faster than anyone can keep up with — but also at the Cool Math For Kids level.

For instance, our children can enjoy Patterns of the Universe, and Prime Climb, and This is Not a Maths Book, and Which One Doesn’t Belong?, and Tiny Polka Dot, and Math & Magic in Wonderland, and Spiraling Pentagons, and …

So many things! I’m sure I forgot one (or several) of your favorite modern-classic math books or toys. I’d love to hear about them in the comments.

And here are a few bits of new playful math. Click, support, and share!

Math Renaissance

In alternating chapters, Rodi Steinig tells stories about her math circle and exactly what happens there, while her daughter Rachel discusses why so many kids hate math, documents the ways math is taught in the classroom — and ways that can be improved.

I first discovered Rodi’s work through her chapter in Sue VanHattum’s wonderful collection Playing with Math: Stories from Math Circles, Homeschoolers, and Passionate Teachers. I’ve been a fan of Rodi’s math circle blog for years, and I can’t wait to get my hands on her new book.

Funville Adventures

When 9-year-old Emmy and her 5-year-old brother Leo go down an abandoned dilapidated slide, they are magically transported into Funville — a land inhabited by ordinary-looking beings, each with a unique power to transform objects.

I had the fun of previewing this book. It’s a cute little fairy tale that should help launch family conversations about math.

Trouble with Monkeys

A boy wants to surprise his dad, but meddlesome monkeys keep getting in the way. The boy is interviewed by the local news, and the story escalates to involve pirates, ballerinas, ninjas — and the magic of our place value number system.

Lucy Ravitch, math blogger and author of The Pancake Menu, teams up with artist Travis Hanson (one of my favorite comic bloggers) to create a story that will build number sense.

This story reminds me of the Cookie Factory Model for long division. Place Value is a key to understanding many things in math.

GregTangMath Home Kit

I haven’t seen these games in person, but they sure look like fun.

And Others?

If you know a project we should all check out, please share in the Comments section below.

Rabbit Trails and Fibonacci Poetry

Homeschool Memories…

Well, I hadn’t planned on spending my day that way. But one of the great things about homeschooling is the freedom to follow rabbit trails.

While browsing the Carnival of Homeschooling, I found a link to Farm School blog’s article Fib Foolery, which sent me to Gotta Book for his articles The Fib and More Fibbery (read the comments on both threads, but be warned that some are crude) and several other posts, all of which set me off on a morning of poetic fun.

A “Fib” is a Fibonacci poem. It’s based on syllable count, like a haiku, but the lines follow the Fibonacci counting series: 1, 1, 2, 3, 5, 8… Each number is the sum of the previous two numbers.

I knew what I was going to share at our Tuesday Teatime and Poetry Reading that afternoon.

Continue reading Rabbit Trails and Fibonacci Poetry

There Ain’t No Free Candy

Ah, the infinite chocolate bar. If only it could work in real life! But can your children find the mistake? Where does the extra chocolate come from?

Here’s a hint: It’s related to this classic brainteaser. And here’s a video from Christopher Danielson (talkingmathwithkids.com), showing how the chocolate bar dissection really works.

Happy munchings!

CREDITS: Feature photo (top) by Yoori Koo via Unsplash. “Hershey Bar Math” video by Christopher Danielson via YouTube. The infinite chocolate gif went viral long ago, and I have no idea who was the original artist.

Playful Math Education Carnival 106 with Math Art

Do you enjoy math? I hope so! If not, browsing this post just may change your mind.

Welcome to the 106th edition of the Math Teachers At Play math education blog carnival — a smorgasbord of links to bloggers all around the internet who have great ideas for learning, teaching, and playing around with math from preschool to pre-college. Let the mathematical fun begin!

By tradition, we start the carnival with a puzzle in honor of our 106th edition. But if you would like to jump straight to our featured blog posts, click here to see the Table of Contents.

Try This Puzzle

If you slice a pizza with a lightsaber, you’ll make straight cuts all the way across. Slice it once, and you get two pieces.

If you slice it five times, you’ll get a maximum of sixteen pieces. (And if you’re lucky you might get a star!)

  • How many times would you have to slice the pizza to get 106 pieces?

Click here for all the mathy goodness!

Dot Grid Doodling

What can you DO with a page full of dots?

Yesterday, I mentioned my new series of paperback dot grid notebooks, and I promised to share a few ideas for mathematical doodling.

But first, let me share my new dot-grid journals for kids. Aren’t they pretty?

Click Here for More Information

Doodling gives our minds a chance to relax, wander, and come back to our work refreshed. And though it goes against intuition, doodling can help us remember more of what we learn.

Math doodles let us experiment with geometric shapes and symmetries. We can feel our way into math ideas gradually, through informal play. Through doodles, our students will explore a wide range of mathematical structures and relationships.

Our own school experiences can make it hard for us to teach. What we never learned in school was the concept of playing around with math, allowing ideas to “percolate,” so to speak, before mastery occurs, and that process may take time.

—Julie Brennan

I like to doodle on dotty grid paper, like the pages in my math journals, but there’s No Purchase Necessary! You can design your own printable dot page at Incompetech’s PDF generator.

Patterns in Shape and Angle

To make a faceted mathematical gemstone, start with any shape you like. Then build other shapes around it. What do you notice? Does your pattern grow outward from its center? Or flow around the corner of your page? How is each layer similar, and how is it different?

Arbitrary constraints can lead to mathematically interesting doodles. For instance, create a design out of 45-45-90 triangles by coloring exactly half of every grid square. How many variations can you find?

Symmetry Challenge

Play a symmetry puzzle game. Draw a line of symmetry and fill in part of the design. Then trade with a partner to finish each other’s doodles.

Make more complex symmetry puzzles with additional reflection lines.

Math Doodle Links

  • Who can talk about mathematical doodling without mentioning Vi Hart? If you’ve never seen her “Doodling in Math Class” video series, you’re in for a treat!
  • See if you can draw a rotational-symmetry design, like Don’s “Order 4” graphs.
  • Or experiment with the more flexible rules in John’s “Knot Fun” lesson.
  • And my latest obsession: the “ultimate” tutorial series on Celtic Knotwork, which explores the link between knots and their underlying graphs.
My favorite knot doodle so far.
Inspirations: A Recreational Mathematics Journal
Reflections: A Math Teacher’s Journal
Explorations: A Math Student’s Journal
Contemplations: A Homeschooler’s Journal

Before you start doodling: How to Break In Your New Math Journal.

Feature photo (top): Sommermorgen (Alte Holzbrücke in Pretzfeld) by Curt Herrmann, via Wikimedia Commons. [Public domain]

Confession: I Am Not Good at Math

I want to tell you a story. Everyone likes a story, right? But at the heart of my story lies a confession that I am afraid will shock many readers.

confessionPeople assume that because I teach math, blog about math, give advice about math on internet forums, and present workshops about teaching math — because I do all this, I must be good at math.

Apply logic to that statement.

The conclusion simply isn’t valid.

Continue reading Confession: I Am Not Good at Math