While the value of backchanneling has been broadly debated among social media enthusiasts, it has not been the subject of scholarly research in secondary schools. This study examined backchanneling, communication apprehension (CA) and student engagement in discussion-based secondary classrooms. This mixed methods study was guided by three research questions. The first focused on how backchanneling affected CA, as measured by pre and post Personal Report of Communication Apprehension (PRCA-24) measure. The second sought to determine if backchanneling affected student engagement. The third focused on how students and their teachers responded to backchannel use. In the experimental design portion of the study, the control and experimental groups were convenience samples of laboratory school students in grades 9–12. CA was measured using pre and post PRCA-24 results; the experimental group received a treatment of at least three rounds of backchannel-supported fishbowl discussions between pre and post PRCA-24 administrations. Paired sample t-tests conducted on both groups compared pre and post treatment CA rates. Data was gathered on student and teacher response to the backchannel via a 12-item online survey combining single choice and open-ended questions. This study revealed unexpectedly high rates of high trait CA, rates two to four times that found among college students in the instrument validation study. It was found that high school students (n=159) preferred backchannel discussions over face-to-face discussions, felt their highest levels of CA in face-to-face discussions, and were most actively engaged in backchannel discussion where they participated three times as often as they did in live discussion. Teacher response to the backchannel corroborated the student findings. Both groups offered guidelines for successful use of backchanneling in the service of teaching and learning. Seventy-four percent of participating teachers reported they were likely or very likely to use the backchannel again. This study contributes new knowledge to an understanding of how to best harness technology in the service of 21^st century teaching and learning.