Thematic Progression and Thematic Repetition in IELTS Essays: Vietnamese Learners Versus a British Expert

Coherence remains a challenge for Vietnamese English learners in argumentative writing, yet comparative evidence regarding regional universities against expert models remains scarce. This study compared thematic progression (TP) patterns and thematic repetition in IELTS Academic Writing Task 2 essays written by 40 third-year English majors at a Vietnamese regional university and 20 model essays written by a British expert writer. All essays were divided into T-units and coded within Systemic Functional Linguistics using a six-pattern TP scheme and three repetition types, with all texts coded independently by two raters. Independent-samples t-tests and Mann-Whitney U tests revealed two mirror-image differences. The students used significantly more Motivated-New transitions (d=1.07) and lexical repetition (r=0.40) than the expert, whereas the expert demonstrated more Rheme-Theme progression (d=1.31) and referential repetition (d=1.24). Theme-Theme progression and textual repetition showed no significant differences, suggesting that connective use is not the primary source of learners’ coherence difficulties. Qualitative analysis further uncovered breakdowns in formulaic introductions, list-style topic sentences, inferential themes, and bare fronted time adverbials. These findings support targeted instruction in Rheme-to-Theme uptake techniques over conventional connective drills. By analyzing learner and expert texts through a replicable framework, this study pinpoints specific learner difficulties in identifiable linguistic operations and translates them into concrete classroom pedagogical targets.