Abstract: In institutional education,different subjects are marked off by their own disciplinary knowledge;language,as the main media of knowledge transmission,is vital for educational practices. We start by reviewing the disciplinary dialogue between Bernsteinian sociology and functional linguistics and Martin's discussion of field and ideation. Based on a case study on spoken and written history,this paper attempts to analyse the differences in ideational system for the "recontextualised" discourses in terms of classification,grammatical metaphor and causal relation. It is suggested that the spoken history is more of "story",while the written history tries every means to distance us from the retrievable past.