Formal and Functional Linguistic Properties of ESL Textbooks

Based on the formal and functional perspectives espoused in Systemic Functional Linguistics (SFL), the main purpose of this thesis was to investigate the extent to which such lexicogrammatical features as lexical density, choice of nominal groups, and grammatical metaphor are used in ESL texts to scaffold target language proficiency levels. Of the number of lexicogrammatical metafunctions and their functional constituents, interpersonal metafunctional categories were analyzed from these three functional features in this thesis in order to reveal the ways in which interpersonal categories and the lexico-grammatical features are correlated as the level of difficulty of each text increases.

The analysis shows that sequential deployment of functional meanings and categories is a crucial feature in the way that ESL texts develop levels of complexity of the target language. This analysis then provides suggestive evidence that because of the significance of these functional grammatical features in science-based genre texts, incorporating more functional grammar approaches to teaching ESL, especially in teaching reading comprehension, might prove to be a more effective teaching strategy than traditional formal grammar approaches allow.