Extant literature on social media in education highlights the importance of improving social media-supported learning environments. This study adds to the literature by examining students' perception and participation for three types of Twitter-based instrumental activities--backchanneling, exploring hashtags, and topics discussion--in two unique undergraduate classrooms (education vs. communication) over the period of a 14-week semester. By employing a comparative case study research design, this study revealed insights into how students may respond to the same Twitter classroom integration activities to a varying degree according to their differences in pre-class perceptions and behavioral patterns. We found that both classes manifested an overall positive attitude toward the integration of Twitter in class along with active participation. However, the communication students manifested a more favorable pre-perception of Twitter and showed a higher participation pattern in class. We also provide pedagogical implications and recommendations for instructors intending to apply or replicate the three instructional activities employed in this study.