by Nicola Davies. 2009. Candlewick Press.

Recommended Ages
Upper elementary and above if you’re reading for information; all ages if you’re reading to notice and learn craft of writing.Just The Right Size: Why Some Animals Are Big and Some Animals Are Little

If you’re not familiar with the work of Nicola Davies, do yourself a favor and get to know this remarkable zoologist turned author. She writes some of the best nonfiction for young readers ever—and this book is no exception. It explains the BTLT (big thing, little thing) rule—or why ants can lift 850 times their weight and we can’t, why geckos can scurry across the ceiling and we can’t, and why birds can fly and we—you guessed it—can’t.

The book is filled with delightful tidbits of information, such as why many insects drink through such long mouth parts, why movie monsters like giant spiders are just so much hocus pocus (their legs would buckle), and why large animals like elephants live on unappealing vegetarian diets of tree bark and wood. No kidding.

It isn’t just the information, however. It’s Davies’ unique way of expressing things: “Big animals are like family cars; they can go for a long time without refueling, and there’s a lot of room for luggage. Small animals are like sports cars: fast, gas-guzzling, and with no room for much more than a picnic!” (p. 48). Her conversational word choice makes scientific information accessible, even for young readers. Her voice makes informational writing as much fun as fiction—and memorable, too. Add the hilarious, whimsical illustrations by veteran artist Neal Layton, and you have a real winner. You won’t want to stop reading; neither will your students. Don’t miss the glossary and index—well done.

In the Classroom…

  • Have students identify a favorite passage from the book and try imitating it in a sample of their own informational writing.
  • How do students like Layton’s cartoon-style illustrations? They might like to try imitating those also.
  • After reading or hearing the book, see if students can sum up the BTLT rule. What’s the essence of it?
  • Have students write a review of the book and post it online—on a school blog or the website of an online vendor.
  • Give students a chance to create a glossary and/or index for an informational piece of their own.
  • What if humans could be extremely big—or amazingly tiny? What anatomical adaptations would be necessary? Would it be worth it? Invite students to write an essay exploring this issue.