Identity through language?
Would that be like identity shown through ethnolects, or features of certain classes of Australian English??
Yeah, you could also add in Teenspeak, etc.
oh ok so any features of language that show someones identity would be your points?
Yeah, that is basically it.
For Identity through language you could talk about Teenspeak with relation to age grading. Age grading means that young people in each successive generation speak like young people and holds the same for middle aged and old people. And this age grading can occur without there being any significant structural change to the language. There are many studies showing that younger people are extremely creative in there language use. The creative use of language, especially the non Standard language is particularly important for social purposes of adolescents when say for instance, creating social connections at school. What young people can do linguistically is extremely important for there identity.
Examples you could use here; double negation, HRT, Teenspeak lexis, etc.
Still on Teenspeak, you could also talk about the effect of the American Culture with it being ubiquitous around the world, especially in Australia. Here you could talk about the change of young Australian's pronunciation, accent and lexical choice due to Americanisms.
Under the topic of Identity you could also talk about ethnolects and note the changes from L1 to L2 that reflect changing identity.