Starred Review ALA Booklist (Thu Apr 28 00:00:00 CDT 2022)

Starred Review In this engaging book on density, Adler explains the concept in terms a child can understand; he does so through straightforward text and basic density-related activities. The brief explanation that something's density is "its weight relative to its size" is useful, but the varied ways of demonstrating the concept are even better. A loosely crumpled ball of aluminum foil floats in water, but a tightly packed ball sinks because of its greater density. A lump of modeling clay sinks, but shaped into a boat that "encloses air," the same clay floats. Other activities show how the density of water changes when it's frozen or made salty. The section on "guessing which things float and which things don't" is particularly fine, not only because it's challenging and fun but also because it leads kids to use elements of the scientific method without mentioning the term. Created with ink washes and drawings and "assembled digitally," Raff's jaunty, imaginative illustrations feature two curious children and their dog playing around with objects and water. It's rare to find a picture book that uses simple hands-on activities so successfully, leading young children to a fuller understanding of a scientific concept.

Kirkus Reviews

A boy, a girl and a dog demonstrate that things float in water when they are less dense than the water around them. Adler, who has demystified math for young readers for years in titles ranging from Roman Numerals (1977) to Millions, Billions, and Trillions (2013) turns his attention to physics with this simple but effective explanation of principles of flotation and density. His clear, logical text invites readers to experiment with different objects, to shape boats, and to make both ice and salt water mixtures. Raff's illustrations take this invitation further, showing a pair of children using toy boats, plastic bottles, pennies, aluminum foil, clay and ice to discover what things float and why. These digitally combined ink washes and drawings add interest and some humor, supporting and enriching the text, except on one page. There, a line showing the water level of a bottle to which salt has been added seems to show that the water level has risen though the author makes clear that the level should not change. Curiously, the series of experiments stops at that point rather than continuing with the denser salt water, as good teachers would encourage children to do. This appealing introduction can serve as a springboard for further investigations. (Informational picture book. 5-8)

Publishers Weekly (Fri Oct 06 00:00:00 CDT 2023)

Adler shows his customary skill for explicating mathematical concepts in this smart exploration of floatation and density. Several experiments allow for a hands-on approach: Adler suggests filling a sink with water and testing whether different objects float, as well as using modeling clay to demonstrate how shape is as important a factor as density. Raff-s pastel palette and cheerful characters keep the mood light and pair well with Adler-s explanations, which are clear without being dauntingly technical. Along with Lynne Berry and Matthew Cordell-s What Floats in a Moat? (reviewed Apr. 29), readers will be well-prepared when it comes to displacement and density this fall. Ages 4-7. Author-s agent: Jodi Reamer, Writers House. (Sept.)

School Library Journal

K-Gr 2 This introduction to density offers new vocabulary in bold font, delightful soft-hued illustrations, and clearly focused content on flotation. The strong examples provide extension activities that can be done at home or in the classroom. The images enhance the concept as readers meet a boy, a girl, and their dog as they embark on an adventure to discover what will float and what won't. For example, a spread depicting how density is relative to the size of the object shows the dog looking over a kitchen sink full of water as a piece of aluminum foil floats as a loose ball and sinks as a tight one. This title supports the Common Core State Standards that focus on measurement skills, interpretation of data, and incorporation of key ideas and details in the text. Recommended for math collections in public and school libraries and classroom shelves. Melissa Smith, Royal Oak Public Library, MI