There are various families of instruments that have physical and sonic characteristics that make them unique, and that are quite common in music classrooms across the world. These families are often made up of: woodwinds, brass, strings, percussion. Most school orchestras are made up solely of strings, and most school bands are primarily made up by woodwinds, brass, and percussion.
Instruments in general give people another medium for expressing themselves. They provide a way to voice feelings without saying a word at all, and this can be an extremely stimulating and fun learning experience for an individual. With an instrument, a person can put more of their feelings out into the world. This is also a great way to teach a child responsibility — instruments demand attention and daily care.