The Effect of Dynamic Assessment of Toulmin Model Through Teacher and Collectivescaffolding on Argument Structure and Argumentative Writing Achievement of Iranian Efl Learners

Considering the paramount importance of writing logical arguments for college students, this study investigated the effect of dynamic assessment (da) of toulmin model through teacher and collectivescaffolding on argument structure and overall quality of argumentative essays of iranian efl university learners. in so doing, 45 male and female iranian efl learners taking part in the study were randomly assigned into three groups (two experimental groups including the teacher and collectivescaffolding and one control group), each consisting of 15 learners. toulmin model of argumentation was used as an instructional tool in this research. the necessary data were collected through a pre and posttest argumentative essay. during the experiment, the dynamic assessment groups wrote and revised their essays in response to teacher’s or peers’ supportive dialogue and zone of proximal development (zpd) sensitive feedback on the argument structure of their essays; whereas, the control group did not receive such mediation and they were evaluated on their own independent performance. the results of statistical analyses carried out on posttest scores on argument structure and overall quality of the essays pointed out to the outperformance of the teacher and collectivescaffolding groups on both variables. furthermore, followup posthoc analyses revealed no significant difference between the teacher and collectivescaffolding groups in terms of the overall quality of the argumentative essays. however, the statistically significant difference between the two experimental groups with regard to the argument structure indicated the outperformance of the teacherscaffolding over the collective group. the obtained results support the fact that autonomy and improvement cannot be thrust upon learners, rather they need to be assisted wisely towards independence.