In these arguments, the criteria for assessing the communicativeness of classroom discourse and, by extension, of teacher talk, are taken from what is perceived to constitute communicative behaviour in the world outside the classroom. The fact that genuine communication appears to comprise characteristics such as ‘negotiation of meaning’ and ‘topic nomination by more than one speaker’ becomes de facto a reason for incorporating them into classroom discourse, and for judging the communicativeness or otherwise of classrooms according to whether or not these features are present. The argument I wish to develop in this article is that attempts to define communicative talk in the classroom must be based primarily on what is or is not communicative in the context of the classroom itself, rather than on what may or may not be communicative in other contexts; and that the application of criteria of communicativeness solely on the basis of social behaviour which exists in certain contexts outside the classroom could result in an inappropriate and ultimately unattainable model for the majority of language teachers to follow, similar to the earlier preoccupation with teacher talking time.

Communication and context
One might, to start with, take issue with the description of authentic communication on which the argument is based. Would it be true to say, for example, that in genuine communication, decisions about who says what to whom are ‘up for grabs’? It might be generally true of informal gatherings of groups of friends, but certainly not of more formal gatherings, such as staff or board-room meetings. Communication at such events tends to follow a very different pattern, determined by their own rules and conventions, but that does not make it any less ‘genuine’ or authentic. Similarly, the classroom, typically a large, formal gathering which comes together for pedagogical rather than social reasons, will also have its own rules and conventions of communication, understood by all those present; these established patterns are likely to be very different from the norms of turn-taking and communicative interaction which operate in small, informal, social gatherings outside. Any analysis of the characteristics of the communicative classroom needs to take these differences into account.

This is not to deny the importance of analyses of the properties of spoken discourse found in contexts outside the classroom (e.g. Hoey 1992) in shedding light on what our wider teaching goals should be, and to that extent suggesting ways in which the discourse of the classroom could be moderated, in order that these goals might be more successfully achieved. But that is a rather different matter from suggesting that classrooms only need to replicate communicative behaviour outside the classroom in order to become communicative.

Features of teacher talk
If we pursue the case for replicating communicative behaviour outside the classroom, there are a number of characteristics of teacher talk which we might identify as being communicative (see Thornbury 1996).
Some of these are: