Control group
The control group received a synchronous course conducted by GDB. The synchronous lesson lasted 2 h, was conducted via ‘Zoom’ in March 2021 and consisted of a frontal lecture using slides and a mobile audience response system (i.e., ‘Mentimeter’). The topics covered were the same as those treated in the asynchronous intervention group. The lectures in the intervention (asynchronous) group were shorter than those in the control group because it is recommended to shorten the duration of asynchronous lectures compared to face-to-face ones to enhance the effectiveness of asynchronous teaching [