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)