- A stopwatch or other timing device

- A measuring tape or other distance-measuring device

- An object that makes a loud sound, such as a starter pistol or a firecracker

1. Choose a long, straight path that is free of obstacles. The longer the path, the more accurate your measurement will be.

2. Place the object that makes the loud sound at one end of the path.

3. Stand at the other end of the path with the stopwatch or other timing device.

4. Start the stopwatch or timing device as soon as you see or hear the object make the loud sound.

5. Stop the stopwatch or timing device as soon as you hear the sound.

6. Measure the distance between the two positions.

7. Divide the distance by the time to find the speed of sound in air.

The speed of sound in air at room temperature (20 degrees Celsius) is approximately 343 meters per second or 1,235 kilometers per hour.