For all three groups, after each student finished his or her turn, the instructor would give immediate feedback to the answers.Before the commencement of the online classes, an online pretest was organized, which was composed of 10 multiple-choicequestions concerning the target learning content (one point for each question). The pretest was employed to assess whether the threegroups had equivalent initial knowledge of the target learning content. The results are shown in Table 1. F