A woodwind instrument is one that typically uses a reed and is made of wood, or was originally made of wood and is now made of metal (flutes or saxophones). A trumped, tuba, and trombone are all brass instruments because they are made of metal and use a mouth-piece instead of a reed. This only leaves the clarinet. Therefore, the clarinet is a wood-wind instrument because it can be made of wood and it uses a reed.
