Which instrument is NOT part of the brass family?

The flute is not part of the brass family because it is classified as a woodwind instrument. Woodwind instruments produce sound through the vibration of air across an opening, while brass instruments create sound through the buzzing of the player's lips against a mouthpiece. The brass family includes instruments such as the trombone, trumpet, and tuba, which all utilize this lip vibration technique in their sound production. Each of these brass instruments also typically has a bell shape and is made of metal, further distinguishing them from woodwind instruments like the flute, which is usually made of metal or wood and uses keys or holes to change pitch. Understanding this classification helps to differentiate how instruments are grouped based on their physical characteristics and the mechanics of sound production.