The longitudinal development of argumentative writing in an English for academic purposes course in Japan

Recent advances in second language (L2) writing pedagogy have placed argumentative writing at the center of the agenda for classroom instruction and research owing to its perceived advantages for developing learners' language, reasoning, and thinking skills. Along with this trend, the assessment of argumentative writing in terms of both structure (i.e., formal elements) and substance (i.e., argument quality) presents challenges and opportunities. In addition, relatively few studies have looked closely at the longitudinal development of argumentation in L2 writing and their range of geographic contexts is limited. Therefore, this classroom study aimed to track the development of students’ argumentative writing over one year of instruction in an English for Academic Purposes (EAP) course at a Japanese university. Samples of argumentative writing were collected from eighteen student writers using a counterbalanced, pretest, posttest, delayed posttest design. These were scored using an analytic rubric that integrates Toulmin-like elements and argument quality. A significant gain was found between the pretest and delayed posttest, which amounted to a 20% score increase. However, progress was also found to vary according to argumentative elements. This development is discussed in terms of teaching practices adopted in the EAP course, including the pedagogical implications of using the Toulmin model in L2 argumentative writing instruction. Limitations including measurement reliability are also considered.