The optimal video length is 6 minutes or shorter -- students watched most of the way through these short videos. In fact, the average engagement time of any video maxes out at 6 minutes, regardless of its length. And engagement times decrease as videos lengthen: For instance, on average students spent around 3 minutes on videos that are longer than 12 minutes, which means that they engaged with less than a quarter of the content.

In a controlled experiment, participants listened to videotaped instruction presented in either narrative or expository form and presented at<br> either a normal or a moderately compressed rate. Results indicate a relationship between organization<br> and retention such that audience members retain more information when it is presented in a<br> narrative style and when it is presented at a normal presentation rate. Practically, the results suggest advantages for narrative form in the everyday practice of instructional communication.