(As the dotted lines indicate, the speaker can become the listener, and vice- versa.)
Closely allied to this general analysis is the concept of the information gap. Suppose, for example, that A (a man waiting for a bus) has the following conversation with B (a woman at the bus stop) :

A: Excuse me, could you tell me the time?
B: Certainly. It's three o'clock.
A may have many reasons for speaking. He may, for example, genuinely want to know the time. In this case he has not got information that B has (the time) and there is therefore a 'gap' in the information they possess. A's conversation is designed to close that gap. If, however, A's question is merely an excuse to get into conversation with the woman, there is still a gap, though of a different nature. Now it is A who has some information (e.g. his desire to engage B in conversation) which B does not possess.
In many really communicative activities where students have a communicative purpose, a gap of this kind will be necessary, for if there is no gap there is often no reason (or purpose) to communicate.

Communicative and non-communicative activities
We can now come to some conclusions about what characterizes a communicative activity. We can say that students must have a desire to communicate, and there must be some communicative purpose to their communication. This implies, of course, that the students' attention will be focused on the content of what they are saying, rather than the form. They will use a wide variety of language, and the teacher will not intervene. (By 'intervene', I mean tell the students they have made mistakes in their English, correct their pronunciation, etc.) In a communicative activity we would not expect the materials which the students were using would control their language (e.g. restrict it to the use of one grammatical form, etc.). These characteristics can apply at one end of a continuum. At the other end of the continuum lie 'non-communicative' activities. For non-communicative activities there will be no desire to communicate, nor will 166 Jeremy Harmer students have a communicative purpose. Where students are involved in repetition or substitution drills, for example, they will be motivated not by a desire to achieve a communicative objective, but by the need to attain accuracy. The emphasis will be on the form of the language, not the content, the teacher will intervene to ensure accuracy, and the materials used will often be designed to concentrate on a particular item of language. We can represent this continuum in the following way: