Following the journal entries of a fictional girl named Sophie York as she conducts interviews and research, readers of this title in the Language Arts Explorer: Energy Lab series are given the mission of investigating water power as an energy source. Using water as an alternative power source, we learn, is not a new phenomenon. Historians and scientists believe water has been used as a power source for millennia. The difference between ancient uses and current or experimental uses involves technology. Sophie interviews a science teacher for a basic understanding; she then interviews experts on a river dam, underwater turbines, tidal power, and wave energy. The book’s appealing layout resembles a lined journal page, though the straightforward text is not especially rich in imagination. Includes colored photographs, a glossary, additional readings, further missions, and an index.