The effectiveness of corpus-based high-frequency word acquisition strategies in improving English writing skills

This study examines the effectiveness of corpus-based high-frequency word acquisition strategies in improving English writing performance among secondary school EFL learners. Grounded in corpus linguistics and scaffolding theory, a quasi-experimental one-group pretest–posttest design was implemented over a 16-week period with 47 Grade 11 students. The instructional intervention integrated the Corpus of Contemporary American English (COCA) into a scaffolded learning framework, guiding students from assisted lexical exploration to autonomous corpus consultation. Quantitative data were collected through four consecutive writing assessments and pre- and post-intervention questionnaires, and analyzed using paired-samples t -tests and effect size estimation. Results reveal a statistically significant improvement in overall writing performance, with mean scores increasing from 13.84 (SD = 2.17) to 18.92 (SD = 2.41), representing a 36.68% gain [ t (46) = 11.36, p < 0.001, Cohen’s d = 1.66]. Sub-dimensional analysis indicates notable gains in vocabulary richness (+48.71%), collocational accuracy (+53.49%), sentence variety (+46.97%), and discourse coherence (+57.03%). Questionnaire results demonstrate enhanced learner motivation (M = 2.83–4.12), with high reliability (Cronbach’s α = 0.89) and strong construct validity (KMO = 0.86, p < 0.001). The findings suggest that corpus-informed high-frequency lexical scaffolding significantly enhances both linguistic competence and learner autonomy in writing.