Innovative educational adaptations have been essential during the COVID-19 pandemic. Against the backdrop of school closures in Hong Kong resulting from unrest and COVID-19, this study proposed using problem-based learning (PBL) in online courses and empirically examined the influence of the PBL learning methodology on online learners' sense of classroom belonging and academic performance. A total of 44 sophomores pursuing electrical and electronic engineering majors and taking "Practical Chinese for engineering students" as a compulsory course at the University of Hong Kong participated in the study. They were divided evenly between the experimental group C1 and the control group C2 (22 in each). We implemented online PBL learning for the experimental group, C1, and traditional online learning for the control group, C2. Quantitative data were collected via an achievement test and a scale on sense of classroom community. Qualitative data were obtained through a semi-structured focus group discussion. The quantitative results showed that the students who received the PBL learning method scored higher on tests, experienced a stronger sense of classroom belonging, and had closer connections with each other. A content analysis of student interviews revealed that implementation of the PBL learning method in online teaching could strengthen students' classroom interactions and that the enhancement of their mutual connections could stimulate learning and improve learning efficiency. Overall, this study finds that the PBL learning method is effective in promoting students' deep active learning and sense of community in the online environment.
Keywords: adapting to online teaching; isolation; problem-based learning.