Why are school bells made up of metal?

Answer: When a material can produce a ringing sound, it is said to be sonorous and metals are inherently sonorous. When a metal bell is struck, the particles that make up the bell begin to vibrate, which are maintained for longer periods of time, resulting in a ringing sound. Because vibrations imply that particles are moving back and forth around a fixed point, we can also claim that metals have elastic qualities.

Thus, the school bells are made up of metal because they are sonorous, have elastic abilities, and can withstand vibrations for longer periods of time.