The present study investigated the use of complex syntax, grammatical accuracy, interaction, argumentation quality and critical thinking in three argumentative tasks of different modalities. The tasks were composed of the synchronous online forums, academic essays and oral debates of EFL undergraduate students (N= 54) enrolled in a 12 week module of English for academic purposes. The methodology encompassed qualitative and quantitative methods of analysis. All data were transcribed and coded qualitatively. Then results were calculated using ANOVA and t-tests to find the differences across...