This study investigated the feasibility of using a web-based Student Response Systems (SRS) to promote interaction in an undergraduate class of 239 students. The study was conducted at a tertiary institution in Guyana, a developing country, faced with technological challenges that made it impractical for every student in the class to respond individually using the SRS. The challenges were addressed by using the Think-Pair-Share model which uses peer discussions, in combination with the shared use of response devices, whereby the large class was subdivided into smaller groups of two to four students, with one student from each group posting the response using the SRS. The Interactivity construct was measured through aspects of learning which included involvement, engagement, participation, feedback and self-assessment. An independent samples t-test was conducted to compare student perceptions of their level of interactivity in class before and after the study. Results indicated that there was a significant difference in their average levels of interactivity before (1.7±0.536) and after the study (4.4±0.483); t = -53.6, p = 0.000 suggesting that the use of shared response devices to post responses in combination with the Think-Pair-Share model can increase individual student interactivity even in a large class.