Experiments using simple lenses, many to be done with the small plastic lens provided. No experiment here is difficult, though adult hands may be useful in the cardboard and Jell-O (yes, Jell-O) construction activities. Explanations are at the simplest level—the word ``refraction'' never appears—and the tone is mostly Socratic. The line drawings, touched with blue, are spritely, but more are needed, especially simpler diagrams. This straightforward introduction to experimentation is an outgrowth of San Francisco's ``Exploratorium''—a museum with 600 hands-on exhibits where ``people make discoveries for themselves.'' No index or bibliography but a list of three sources for lenses. (Nonfiction. 8-11)