While knowing that students lose their focus on lecture after twenty minutes, due to the inefficiency of moving between classes every twenty minutes, universities timetable lectures for an hour up to even three hours. Nevertheless, e-learning has made it more practical.
This has been completely explained in the following two publications:
Kinchin, I. M. (2016). Visualizing powerful knowledge to develop the expert student: A knowledge structures perspective on teaching and learning at university. Springer:
Many curriculum structures within universities have long historical origins and are bound up with issues such as internal politics and research funding as much as they are to do with any underpinning pedagogical claims. However, that is not to say that they cannot evolve and outgrow some of the more dated and restrictive practices that have helped to shape them. For example, that universities still tend to timetable lectures for about an hour even though we ‘know’ that students will typically only concentrate for about twenty minutes of that hour is a practical outcome of the logistical impracticality of moving in and out of classes every twenty minutes.
O'Flaherty, J., & Phillips, C. (2015). The use of flipped classrooms in higher education: A scoping review. The Internet and Higher Education, 25, 85-95.
I was wondering if there is any experimental evidence that having breaks every 20 minutes in classes is not practical, or it is just a common belief and no one has ever tried it?
This thread answers many concerns mentioned in the comments.