Vietnamese EFL Learners’ Productive Derivative Knowledge: Contextualized Derivative Recall Test Performance and Its Relationship with Derivative Misuse in Argumentative Essays

This study measured EFL learners’ productive derivative knowledge via a contextualized derivative recall test and explored its relationship with the misuse of derived forms in argumentative essays. Data were collected from 88 third-year English majors at a university in Vietnam, each writing an argumentative essay in their normal class hours and subsequently taking a contextualized derivative recall test of 30 target headwords. Test data were scored for the successful production of the target derivatives in two methods: headwords counted (HC) and headwords not counted (HNC). In addition, the argumentative essays were analyzed for derivative errors committed. Results indicated that these students were able to produce, on average, 52% and 44% of the target derivatives in the HC and HNC methods respectively. They were most successful with high-frequency target words, and accurate production rates were found to be subject to the scoring methods and derivatives’ parts of speech. Regarding erroneous use of derivatives in written essays, misuse of word parts of speech was more prevalent than others. In addition, there was a significantly positive correlation between the derivative recall test scores and the derivative errors in written essays, but only in the HC method. All these findings suggest that learners’ productive derivative knowledge may be influenced by numerous factors, and derivative recall test performance might not equate accurate use of derived forms in writing, thus providing important implications for assessing L2 productive derivative knowledge and instruction.