In synchronous learning, participants interact by viewing each other directly. Deactivation of the video camera and low student involvement can be interpreted variously, including learning seriousness or lack of it, physical presence in the virtual classroom, etc. We studied the connection between video camera use, class involvement and student achievement in a one semester psychometry class. We monitored camera use and class involvement and captured final grades, supplemented with an open-ended questionnaire and semi-structured interviews. A combination of turning a camera on and active participation in the class affected the student grade more strongly (p = 0.88) than class involvement (p = 0.12). Bayes factors showed that a model, enhanced by both activated cameras and student involvement, was 7.14 times more likely to affect grade. Bayes linear regression predicted class participation increased the grade by 3.2 points per meeting, whereas turning the camera on increased it by only 0.9 points per meeting. However, both involvement and turning the camera on were predictors of student achievement. Questionnaire responses showed reasons not turning a camera on included unready to learn (44%), unstable internet connection and limited quota (37%), psychological reasons (11%), devices overheating (4%) and following others (4%). On the other hand, students always turned the camera on because of communication support (49%), evidence of seriousness (25%) and attendance (16%), following others (1%), good internet connection (1%), and respect for the instructors (8%). The students who activated their camera felt supervised and it forced them to study seriously and maintain concentration during class.