Been looking at online learning and how it works best. This article from behavioural scientist talked about the “Flipped Classroom”.
A flipped-classroom approach typically involves students reading texts or watching recorded lectures outside of class then using the in-person class time to work collaboratively on activities and engage in discussion about the material.
The efficacy of this pedagogical approach is strong: there is a continuously growing body of evidence that courses promoting active learning are most effective for student learning overall, and for underrepresented students in particular.
And this research suggests that watching a video at double speed actually works as well as listening at normal speed (and takes half as long). And that re-watching at double speed before an exam works even better for retention!
See also this post on online learning