Use of the Inflectional Morpheme -s Marking Plurality and the Third-Person-Singular Present Tense in Vietnamese EFL Opinion Essays: Accuracy Analysis and Learner Perspectives

The present research explored how Vietnamese EFL third-year students used the inflectional morpheme –s marking plural nouns (PN–s) and the third-person singular in the present tense (3SG–s) in opinion essays. 32 students each wrote an opinion essay about the topic of Facebook within 45 minutes as a progress test. The collected essays were analyzed for the use of PN–s and 3SG–s. 10 of the students who had completed their writing task were subsequently interviewed in an in-depth semi-structured format. The results revealed that students used PN–s and 3SG–s correctly in most of the obligatory contexts. Yet they used PN–s more accurately than 3SG–s. Omission was the most common error students made, and they omitted 3SG–s at a higher rate than PN–s. In view of the plural morpheme, omission of the orthographical plural variant –s was significantly higher than that of –es and of –ies. Incorrect use rarely occurred. But when it did, it was only found with PN–s, which also had a higher rate of oversuppliance than 3SG–s. In the interviews, the students reported having explicit knowledge about the target morphemes, but different factors related to the meaning-making process involved in essay writing contributed to omission or misuse. The study offers important pedagogical implications for writing instruction and teacher feedback that enhance the use of the target morphemes in written language production.