The Impact of Morphological Awareness of Affixes on Vietnamese EFL Students’ Ability to Infer Word Meaning and Word Class in Reading: A Case Study in VMG English Center

Abstract

This study investigates the impact of explicit morphological instruction (EMI) of affixes on Vietnamese EFL students’ ability to infer word meaning and identify word class while reading. A quasi-experimental design was employed with 60 students (aged 14–17, B1 level) at a private English center, divided into an experimental group (n = 30) and a control group (n = 30). Both groups completed a pre-test and post-test measuring word-meaning inference and word-class identification; the experimental group received six weeks of EMI targeting prefixes and suffixes, while the control group followed traditional instruction (rote memorization and textbook-based instruction). A 17-item Likert-scale questionnaire (Cronbach’s α = 0.70–0.87) and a classroom observation checklist provided supplementary evidence. Results showed no baseline difference between groups (p > 0.05), but after the intervention the experimental group significantly outperformed the control group in both inferring word meaning (M = 3.58 vs. M = 2.19, t(58) = 7.20, p < 0.001) and identifying word class (M = 4.42 vs. M = 3.54, t(58) = 4.89, p < 0.001). Questionnaire results further indicated strongly positive student perceptions of morphological awareness across cognitive, affective, and behavior dimensions. The findings support explicit affix instruction as an effective strategy for improving vocabulary inferencing and reading comprehension among Vietnamese EFL learners in private-center settings[cite: 10].