Book review by
Jan Carr, Common Sense Media
Triangle Book Poster Image
Shapes play pranks in simple, funny friendship story.

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A lot or a little?

The parents' guide to what's in this book.

Educational Value

Teaches two shapes, triangle and square, which are repeated frequently in the art. Being able to distinguish shapes is a prerequisite for learning letters and reading.

Positive Messages

Implicit message that kids can learn and master shapes. Friends who are different and live in different worlds can still be friends.

Positive Role Models & Representations

Though Triangle and Square are different and come from different worlds, they're friends. Their friendship, however, is based on playing practical jokes on each other, one scaring the other.

Violence & Scariness

What parents need to know

Parents need to know that Triangle is by Mac Barnett and Jon Klassen, two comedians who've teamed up successfully before (Sam & Dave Dig a Hole). It teaches two shapes, triangle and square, through repetition and humor. The friendship of the two shapes isn't warm and fuzzy: Triangle plays a "sneaky trick" on Square by hissing when he knows Square’s afraid of snakes, and Square gets back at Triangle, who's afraid of the dark. So parents looking to cultivate empathy might look elsewhere. But kids looking for sneaky, silly humor will recognize themselves in the characters. And by the end of the story, they'll also likely be experts at recognizing these two shapes.

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What's the story?

The title character TRIANGLE lives in a triangle-shaped house with a triangular door. He decides to go visit his friend Square and play a "sneaky trick" on him. To get there, he has to walk through a stretch of "shapes with no names" and then to "a place where there were squares." He arrives at Square's square house, walks up to Square's square door, and, because he knows that Square is afraid of snakes, he hisses. Square, angry, chases Triangle back to his house. But when he tries to run through the triangular door, he gets stuck, blocking the light. Now it's Triangle's turn to be afraid since he's afraid of the dark. Square says, "Now I have played a sneaky trick on you! You see, Triangle, this was my plan all along." The book ends with the question, "But do you really believe it?"

Is it any good?

Two shapes who are friends are also merry pranksters who enjoy a good practical joke in this story about a feisty friendship between a triangle and a square. The cover of Triangle shows the titular character but no title, and Mac Barnett’s text is as deadpan. It's fun that the place Triangle lives is completely triangular, while Square's world is just as square. And in between there’s a mysterious stretch of rocky shapes with no names. These friends have to travel far to see each other and are not above giving each other a good scare.

Illustrator Jon Klassen draws Triangle and Square with stick legs and his characteristic shifty eyes. The art is blocky and earth-toned and the vistas vast. Kids will enjoy the fun and come away with a solid grounding in two shapes.

Talk to your kids about ...

  • Families can talk about the shapes in Triangle. What shape is your house? Your doors?

  • What other things can you think of that are shaped like triangles or squares?

  • Would Triangle fit in Square's door? Can you think of a way two triangles could fit?

Book details

Our editors recommend

For kids who love picture books and friendship tales

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