Things That Float and Things That Don't

David A. Adler’s direct, accessible text uses an engaging, hands-on approach: almost immediately readers are encouraged to fill their sinks, find things around the house “that won’t be damaged by water,” and guess which will float before putting them to the test. Activities throughout—using common objects such as aluminum foil and water—bring the explained concepts to life. As an illustration of the principle of density, for instance, kids are instructed to take a lump of modeling clay and place it “on the surface of the water in your bath. It sinks. Now let’s make it float.” By forming the same clay into a boat, kids will see firsthand what happens when the shape changes. Adler handily relates the experiments’ findings to the larger world. The clay boat activity, for example, shows why large ships, which may weigh thousands of pounds, float. Similarly, a simple experiment with water demonstrates why ice and icebergs float. Anna Raff’s pastel-toned, child-like artwork shows a boy and girl conducting the experiments while their dog looks on. The illustrations maintain a light-hearted feel while featuring points from the text.

Adler expertly teaches the concept of density, moving beyond the classic floating and sinking experiments to a carefully constructed lesson that helps young thinkers appreciate both scientific explanations and practices. The treatment of density is masterful: Adler introduces the fundamental physical relationship with terms familiar to readers (weight relative to size), then gradually builds to the scientific definition through examples and ideas that draw on intuitive, everyday experiences. By the end of the book, the term density is employed accurately and easily within sentences that fully summarize its meaning. Although hands-on experimentation is encouraged, equal time and effort is appropriately spent on scientific reasoning and thought experiments triggered by perfectly targeted questions. The concepts are kept simple and age appropriate, yet without shying away from the more abstract dimensions of science. This takes readers well beyond vocabulary memorization into true science comprehension. Cartoonlike illustrations portray two children and their scientifically curious dog happily doing science. danielle j. ford