Just the Right Size: Why Big Animals Are Big and Little Animals Are Little
Grade 4–8—This unique title uses geometry to discuss the varying strengths and capabilities of different animals. In a chatty tone, Davies starts off by describing the strict rules that control what bodies can and cannot do. She goes on to explain how the strongest animals are much smaller than humans. "Some important features of bodies—like how much food and air they need—depend on volume and weight. Others—like the strength of muscles—depend on cross section or surface area." This is the basis for the BTLT (Big Thing, Little Thing) Rule: "If you DOUBLE the length of something, its surface area and cross section go up FOUR times, while its volume and weight go up EIGHT times!" BTLT is used throughout to explain why humans cannot fly, yet Arctic terns can travel 20,000 miles every year from pole to pole and back again. Humans cannot lift buses, but the rhinoceros beetle can lift 850 times its own weight. The author uses clear language and engaging examples throughout. Cartoon illustrations add humor and clarity to the book. A handy introduction to animal sizes.—Anne Chapman Callaghan, Racine Public Library, WICopyright © Reed Business Information, a division of Reed Elsevier Inc. All rights reserved.