Describing the concept of time and how it has been measured, Koscielniak gives an instructive yet entertaining march through the ages. A two-page explanation of daytime versus nighttime, as well as the seasons, sets the stage for the beginning of timekeeping and the origins of the Gregorian calendar. The author provides just enough detail for readers to understand how sundials and water clocks work and to comprehend the problems with their accuracy.
Attractive watercolor illustrations in green and tan tones enhance the text. Detailed diagrams further explain such concepts as Huygens's balance spring, which later developed into the portable watch. Endpapers show various timepieces through the ages from an Egyptian shadow clock in 1500 B.C. to electric clocks in A.D. 2000. Children (Grade 3-5) will be entertained as well as informed by this presentation.