Functional grammar has a number of features which make it suitable for studying language variation.
* Firstly, it is based on the notion of choice - it models grammar as a set of options (a repertoire or resource). This means that it presents grammar to teachers and students as a set of tools they can use rather than a set of rules about what not to do.
* Secondly, functional grammar looks at the way in which grammar is used to construct texts in their context of use - it is concerned in other words with real language not just with the made up examples of language that can be found in many language tests, exercises, work sheets or traditional grammar books. Its application is not restricted to the analysis of isolated sentences - it explains the way in which sentences are structured to construct whole texts such as stories, essays and reports which students learn to read and write in primary and seconday school.
* Thirdly, functional grammar is concerned with the way in which grammar is organised to make meaning. Because it is concerned with meaning, it can be related directly to the concerns of teachers and students in all subject areas.
Overall, functional grammar is concerned with the way that the different kinds of meaning that contribute to grammatical structure are comprehensively addressed. It is concerned with resources for
* analysing experience - what is going on,
* analysing interaction - who is communicating with whom
* analysing the ways in which messages are constructed
In order to model grammar as a context sensitive, meaning-making resource, functional grammar looks closely at the different contributions made by clause, phrase and group and word structure to a text.
* At the clause level, functional grammar deals with resources for
o analysing experience (Process type, Participants and Circumstances),
o participating in communication (mood and modality)
o packaging information (theme and cohesion)
In addition it is concerned with resources for combining clauses into clause complexes (sentences).
* At the phrase and group level, functional grammar deals with resources for
o constructing Participants (noun groups)
o assessing events and setting them in time (verb groups).
o modifying events (adverb groups)
o qualifying Processes (preposition phrases)
* At the word class level functional grammar is concerned with resources for adapting words to clause, phrase and group structures
* Within words, functional grammar is concerned with resources for analysing morphemes (inflection and derivation).
Because the study of language structure has not been an explicit part of teacher education for some decades, a technical approach to language is unfamiliar to many teachers. However the resources described above are regularly used by speakers and writers to make meaning in speech and writing. Bringing these resources to consciousness provides a powerful tool for teachers and students to use in comprehending and composing texts within contexts.
[Source: Christie, F. (1991) What is functional grammar? in Teaching English Literacy, pp. 106-107 ]