Explore the many ways in which time is measured. Includes questions and activity guide. There are many units with which to measure time, including seconds, hours, days, and even decades. Clocks and calendars make it easier to see time pass, but time is always moving even when we arent measuring it. Beginning with the sundials of the ancient Egyptians, readers will learn much more than just how to measure time. Simple explanations of time zones and the inner workings of classic and modern timepieces accompany brief introductions to some of the greatest scientists to study time. Engaging questions and a hands-on activity guide them through this important math concept.