Stopwatch

measuring time · sports · super useful

Measures elapsed time. A stopwatch starts counting the moment you press a button and stops counting the instant you press it again, telling you exactly how many seconds, minutes, or hours passed between those two moments.

Perfect for racing. Athletes and coaches use stopwatches to measure how fast runners complete races, how quickly swimmers finish laps, or how long someone holds a position in gymnastics.

Digital and mechanical. Stopwatches can be mechanical devices with hands that spin around a dial, or digital ones that show glowing numbers on a screen, and nowadays your phone has one built right in.

Timing in science. Scientists use stopwatches during experiments to record how long chemical reactions take, how fast objects fall, or how quickly plants grow under different conditions.

Ancient invention. People have been trying to measure short bursts of time for hundreds of years, from simple hourglasses to the precise stopwatches we use today.