Media multitasking is a common artifact of the increasing presence of technologies in classrooms. However, research indicates learning decrements when students engage in inappropriate or "off-task" media multitasking during class time. This is a concern as many innovative teaching practices call for the use of technologies. The present study examined 'on-task' (using media technologies to support learning) and 'off-task' multitasking when students were required to use online demonstrations as part of a collaborative group work activity within three regular, live classroom sessions. In total, 107 introductory psychology students participated as part of their regular classroom instruction. Both survey measures and direct observation indicated that students engaged in both on-task and off-task multitasking during the online and face-to-face group work components. Fewer students reported going off-task than expected. The proportion of students engaging in multitasking increased over time from the first to third demonstrations. Interestingly, perceived relevance of the online demonstrations predicted on-task behaviors. Overall, outcomes suggested that employing relevant online activities as part of ongoing instruction fostered more on-task behaviours and were perceived to be relevant learning tools. Implications for instruction are discussed.