A corpus-informed study of lexical and grammatical features in IELTS graph description tasks by high and low proficiency writers and the development of IELTS preparation materials for low proficiency learners

The research study placed an emphasis on teaching integrated writing since it has been prevalent in international standardized tests. To address the challenges from linguistic issues in writing skills, corpus-based analysis which involves learner corpora and genre-based teaching approach was applied in the present study. Primarily, this study aims to examine typical lexical and grammatical patterns used by high proficiency writers when taking IELTS writing task 1, to investigate the differences between low and high proficiency writers’ line graph descriptions, and to explore the extent to which the corpus-based materials along with genre-based teaching approach can develop low proficiency learners’ writing skills. Two corpora were constructed from 47 IELTS writing task 1 models (6.0-9.0 band) and 12 essays by high schoolers (2.0-4.0 band) and were then validated by two professional writing instructors. Antconc software was implemented to analyze both corpora. Afterwards, the quantitative data were identified and categorized based on elements of a graph description. Correspondingly, the underuse, overuse, and misuse of lexical and grammatical patterns among LPWC compared with those of HPWC were examined based on Keyness analysis and concordance line observation. The findings suggest frequent lexical and grammatical patterns used by high proficiency writers in each element and throughout the essay. Also, it is determined that while high proficiency writers demonstrated a wide range of lexical items and some certain grammatical patterns, low proficiency writers employed a limited range of vocabulary coupled with inaccurate grammatical structures in their graph descriptions reported as the underuse, overuse, and misuse. Interestingly, the implementation of corpus-based materials coupled with genre-based approach can, to some extent, help enhance low proficiency learners’ writing skills in terms of lexical and grammatical patterns as well as writing organization. The study further suggested that EFL instructors allow such learners to explore more writing models, do exercises with effective tasks, and learn from the underuse, overuse, and misuse made by Thai EFL learners so that they could absorb and produce appropriate language accordingly.