The major objective of this experimental research was to assess the differences between two varieties of focus on form instruction, namely proactive and reactive across multimodal vs. traditional input settings in both comprehension and production of modal auxiliaries. The participants of the study were 75 Iranian English as a foreign language (EFL) high school students at the elementary level in three classes. The students in each class took part in a pre-test including both comprehension and production items. Then, they were randomly exposed to one of the three types of grammar instruction, i.e. proactive focus on form in which students were exposed to multimodal input through preplanned techniques of input enhancement and input flood, reactive focus on form in which the tasks occurred in multimodal episodes including negotiation and correction by the instructor through recasts, clarification requests, and repetition techniques. Lastly, in the control group, the students were provided with a pamphlet and their teacher’s explanations. The post-test was then administered to the three groups, and the results were analyzed by conducting a one-way-analysis of covariance (ANCOVA) which revealed a significant difference among these three groups. The results showed that the proactive group outperformed the reactive and control groups both in the comprehension and production of modal auxiliaries. At the end of the experiment, a brief survey which was accomplished through an interview revealed that the majority of the students highly favored PowerPoint presentations, teacher's explanations, and video clips respectively.
