The basic idea in listening tasks is for some action to be taken on the basis of information which is heard, with or without accompanying visuals. Input is generally localized to a single source - the teacher, a student, or an audiotape or video clip - and students generally work individually to make use of the input, so that spoken production will not be called into play.
The teacher's strategy is based on designing a "receptacle" for the flow of information. This "receptacle" can be a choice students make, a drawing they produce, objects they place in order, an action they perform, etc.
Since listening is a receptive skill, in each of these cases the "transaction" is one-directional. That makes these tasks relatively uncomplicated in communicative terms, since there is no negotiation. Even though listening tasks are simple in communicative terms, the technical requirements for various tasks can differ considerably, calling for different kinds of "shots" and the use of various equipment.