Explain how sound is produced by your school bell.
The sound of the bell depends upon the vibration of the bell when it is rung. When the bell starts ringing, it drives the molecules around the air to vibrate. This produces the wave. So the compression is produced, however, the rarefaction makes the sound echo through the air. Since, the vibrating molecules put pressure on one another, which in turn air particles are disturbed and start moving forward and backward.
