With excitement and solid fact, Wells introduces the concept of time and how we measure it. The science is complex, whether Wells is considering time zones, changing seasons, or atomic clocks; but the picture-book format, with pen and acrylic illustrations of a boy, a girl, and a dog, roots the concepts in daily experience. The historical approach--from the sundial and the ancient Roman calendar to the pendulum and then quartz crystals--provides a step-by-step introduction to the amazing technological discoveries. Wells' chatty informal style will certainly help adults talk about the concepts with children, though the exclamatory tone and punctuation in almost every sentence are unnecessary. The amazing facts say it all. Hazel Rochman Copyright © American Library Association. All rights reserved