Speaking is a productive language macroskill.
However, it does have the advantage of being a natural skill — everybody (almost) has naturally learned to speak at least one language, whereas activities such as reading and writing need to be explicitly taught.
Although it may seem to be obviously impossible, some students sometimes seem to feel that they can improve their speaking ability without actually speaking. It must be pointed out to them that they can no more learn to speak by listening to other people speak than they can learn to ride a bike by watching other people ride, or learn to play the piano by watching other people play. Speaking is as much a physical skill as a mental one and — in common with all physical skills — the only way to improve it is by constant practice.