Stopwatch facts for kids
A stopwatch is a tool used to measure the amount of time something takes. For example, to learn how soon a car can reach 60 miles per hour, or how much time it takes a runner to run 40 yards. These days, stopwatches are even installed in digital watches. You press a button to start the time and press it again to stop the time. The time is displayed on the screen of it. It even tells you the millisecond!
Stopwatch Facts for Kids. Kiddle Encyclopedia.