The Language of Vietnamese School Science Textbooks: A Textual Analysis of Ten Lessons (Texts) of Biology 8.

This article investigates the textual meanings realized through theme resources in a Vietnamese lower secondary school science textbook, Sinh học 8 (Biology 8), using Systemic Functional Linguistics (SFL) as the analytical framework. Analyzing ten selected texts from the textbook, the study focuses on major independent clause simplexes and hypotactic clause complexes to identify types and patterns of Themes, including simple, multiple, clausal, unmarked, and marked Themes, as well as their distribution across mood functions such as Subject, Predicator, Complement, and Adjunct Themes. Key findings reveal that simple Themes, particularly Subject Themes in declarative clauses, predominate, and that Vietnamese textbook writers employ a variety of thematic patterns—mainly textual + topical and interpersonal + topical—to construct coherence and continuity in the texts. The study also notes the absence of certain Theme types (e.g., Complement Theme) and highlights the role of spatial and temporal Adjunct Themes in creating textual cohesion. The research suggests further exploration of thematic progression and thematic structures beyond the clause level in Vietnamese educational texts.