This study assessed the impact of teachers' assertive classroom management on the students' perception of classroom activities and their goal orientations. It adopted a mixed method approach (QUANTITATIVE? qualitative.). The population consisted of about 590 consisted of Iranian university and institute students out of which 147 were sampled. They were administered three questionnaires and five were interviewed. To gauge teachers' assertive classroom management, we utilized a questionnaire developed by Shawer (2010). It includes 37 items measuring four components of teacher's assertive classroom management (organization, teaching strategies, teacher-student relationship strategies, teacher's punishment-reward strategies). To assess students' perceptions of classroom activities, a scale designed and validated by Gentry and Gable (2001) was utilized. It comprises 31 items and consists of 4 components (interest, challenge, choice, and joy). The students' goal orientations were measured via 'achievement goal orientation inventory' designed by Midgley, et al. (1998). The inventory comprised three subscales (mastery-approach, performance-approach, performance-avoidance approach) and a total of 18 items. In the quantitative phase, the results demonstrated that teachers' assertive classroom management strategies predicted students' perceptions of classroom activities exhibiting the highest influence on challenge and interest respectively. Mastery goal was influenced by teacher assertive classroom management strategies. The results of the quantitative phase confirmed the findings of the quantitative phase.