This paper was published in the Handbook of Educational Linguistics, Blackwell 2008, edited by Bernard Spolsky and Francis Hult (pp 53-65). The paper was written in June 2006.
I distinguish between two parts of theory: individual ideas (e.g. descriptivism) and models (e.g. models of language change or grammatical structure), and argue that ideas are much more relevant to education than models are. I list some of the main ideas and briefly summarise the most general 'super-models' relevant to education - generative, systemic and cognitive. I warn against uncritical acceptance of the systemic model.