Which One Doesn't Belong?: Playing with Shapes

by Christopher Danielson

Overview

Talking math with your child is simple and even entertaining with this better approach to shapes!

Written by a celebrated math educator, this innovative inquiry encourages critical thinking and sparks memorable mathematical conversations. Children and their parents answer the same question about each set of four shapes: "Which one doesn't belong?" There's no one right answer—the important thing is to have a reason why. Kids might describe the shapes as squished, smooshed, dented, or even goofy. But when they justify their thinking, they're talking math! Winner of the Mathical Book Prize for books that inspire children to see math all around them.

"This is one shape book that will both challenge readers' thinking and encourage them to think outside the box."—Kirkus Reviews, STARRED review

Product Details

ISBN-13:	9781580899468
Publisher:	Charlesbridge
Publication date:	02/12/2019
Edition description:	Reprint
Pages:	40
Sales rank:	482,068
Product dimensions:	8.30(w) x 8.30(h) x 0.20(d)
Age Range:	4 - 8 Years

About the Author

Christopher Danielson has taught math to learners of all ages. He now uses his PhD in mathematics education to create books and toys to support children's math development. Christopher is the developer of Math-On-A-Stick, an annual family math event at the Minnesota State Fair.

Read an Excerpt

This book is different from other books about shapes. Every page asks the same question, and every answer can be correct. 

Look at these shapes. There are many ways they are alike and different. Pick out a shape that seems different from the others. 

Which one doesn't belong? Why?

Editorial Reviews

♦ A math concept book that encourages creative thinking and celebrates all answers, as none are wrong! A lengthy introduction of five and a half spreads introduces readers to the kind of mathematical thinking Danielson is encouraging. The first spread matches the final ones and presents four shapes, asking readers: "Which one doesn't belong? Why?" The next spreads explain how every answer is correct—one needs only to support it. Is it the triangle among the quadrilaterals? The one shape that is an outline instead of a solid color? Nine spreads then follow that each present kids with four new shapes and the same questions, bold colors attracting and holding interest as kids pore over the similarities and differences. The author's note emphasizes that "All properties count here; all ideas matter….You're thinking in a mathy way when you notice sameness and difference for one property at a time." And refreshingly, Danielson doesn't care about technical language—observations trump terms, so don't worry about describing them as "smooshed…dented…or colored in"; just describe them. This is one shape book that will both challenge readers' thinking and encourage them to think outside the box.

—Kirkus Reviews, STARRED review

If I had to choose only one book from this list to give to a kid in my life, this might be the one. It allows children to do mathematics in a really exciting way that mimics what mathematicians do. They discuss math with colleagues; they create arguments about their findings. This book, which seems simple on the surface — find the shape that doesn’t belong — creates rich scenarios with multiple possibilities for correct answers. The explanation is more important than the answer, which is how deep understanding of mathematical knowledge is demonstrated.
—Book Riot

From the Publisher