The Effects of Morphological Awareness on L2 Vocabulary Knowledge of Thai EFL Young Learners

Morphological awareness (MA) is the ability to recognize words, identify the association between lexically attached parts of a word and create new lexical forms. Morphological instruction mediates the acquisition of new words and is, therefore, crucial for developing morphological awareness and vocabulary knowledge. Currently, the receptive-productive continuum of MA remains unclear, especially in an EFL context. This quasi-experimental study investigates how MA instruction affects the acquisition of morphologically complicated words and its impact on vocabulary knowledge among young Thai EFL learners. Six receptive and productive MA measures and four vocabulary knowledge measures were administered to 221 EFL young learners. While participants in the control group did not get this instruction, participants in the experimental group received explicit teaching on morphological awareness. A repeated measures ANOVA (with scores on several aspects of affixes as the dependent variable) with experimental and control cohorts and a repeated measure (time point) was conducted to probe Thai young EFL learners’ morphological awareness and vocabulary knowledge. The findings demonstrated an encouraging effect of MA teaching in English language classrooms. Specifically, the participants in the experimental group showed improved performance in both receptive and productive MA. This suggests that the explicit instruction of morphologies may benefit English learners in understanding words and ease vocabulary acquisition. Other implications of these findings are debated, considering current pedagogical practice and theory.