Interest recently has increased in encouraging students to write for a particular purpose, for a known audience, and in an appropriate form. However, what constitutes an appropriate form is often dealt with in very general terms such as the listing of different types of texts, for example, "notes, letters, instructions, stories, and poems in order to plan, inform, explain, entertain, and express attitudes or emotions" ( England Department of Education and Science, 1990).

This listing of text types implies that teachers and students know what distinguishes the form of one text type from another. At a certain level, of course, this is true -- for example, we all know what a story is like and how it differs from a recipe. Most of us are aware that a narrative usually has a beginning, a series of events, and an ending, and that many teachers discuss such ideas with their students. It is still relatively rare, however, for teachers of elementary students to discuss nonfiction texts by drawing on students' knowledge of the usual structure of a particular text type to improve their writing in that form.

It has been argued (Martin, 1985) that our implicit knowledge of text types and their forms is quite extensive and that one of the teacher's roles is to make this implicit knowledge explicit. Theorists in this area are often loosely referred to as "genre theorists" and they base their work on a functional approach to language, arguing that we develop language to satisfy our needs in society (Halliday, 1985). These theorists see all texts, written and spoken, as being "produced in a response to, and out of, particular social situations and their specific structures" (Kress & Knapp, 1992, p. 5). They therefore put stress on the social and cultural factors that form a text as well as on its linguistic features. They see a text as a social object and the making of a text as a social process, and they argue that in any society there are certain types of text -- both written and spoken -- of a particular form because there are similar social encounters, situations, and events which recur constantly within that society. As these events are repeated over and over again certain types of text are created over and over again. These texts become recognised in a society by its members, and once recognised they become conventionalised, that is, they become distinct genres.