Measuring derivational knowledge of Chinese EFL learners: the effect of explicit instruction

Recent research has endeavored to measure English as a Foreign Language (EFL) learners' receptive and productive derivational knowledge (DK). However, it is still unclear how well Chinese university EFL learners master DK and how this knowledge develops with explicit instruction. This study addressed these issues using a pretest-posttest quasi-experimental design with a three-month intervention. 120 participants divided into control (n = 53) and treatment (n = 67) groups by a convenience sampling took the receptive Word Part Levels Test (WPLT), the productive sentence completion test (SCT) and the sentence writing task (SWT). Linear mixed-effects models and pairwise comparisons showed that the learners could only correctly recall half of the derivatives for the gap-filling SCT and obtained about one-fifth of the total possible score in productive use of derived forms in the SWT, despite relatively good mastery of receptive affixes. Moreover, the instruction had a robust improving effect on the ability to recall derivational forms and slightly increased the receptive affix knowledge. However, the short-term derivational intervention produced no significant effect on the ability to use different derived words to write sentences. Pedagogical implications on the EFL DK development and instruction were discussed.