Why is an accordion a woodwind instrument?

It is a woodwind instrument because, like other woodwinds, it also uses reeds. Think about a Clarinet, for example. Clarinets are woodwinds because when you blow on them, the reed vibrates and makes a sound. Accordions are like having a bunch of different reeds all contained in one instrument. When you press a key down, it opens a reed so that air can flow over it and it can vibrate. Then you have to move the bellows to get air moving over the reed. Since it has reeds, it can be thought of as a woodwind instrument. However, it must be noted that the reeds are usually made of steel, not wood.