Reading vs. watching a lecture: which activity results in higher knowledge retention? I teach calculus to freshmen and currently spend most of the classroom time lecturing. To make classes more interactive I'd like to shift this phase of "knowledge transfer" outside of classes. Either by giving students reading assignments, or by giving them videos to watch.

So I was wondering if reading as opposed to watching a video of someone explaining the same thing, results in different learning outcomes.

An attempt to make the question more narrow: is there a difference in brain activity or knowledge retention between reading a text vs. watching another person reciting the same text?
Consider this, communication is more than 50% nonverbal. Studies vary (from 93% nonverbal to 75%) and the actual percentage is difficult to interpret, but it is generally accepted that most of the communication is nonverbal.
That being said, a book is only written word and content, whereas a lecture is dynamic, versatile, and incorporates much of the nonverbal content.
Moreover, a lecture and video has much more stimulus going to the brain and this does have an impact on memory retention. Consider how PTSD cases arise; they are due to an individual experiencing hyper-stimulation (from the emotional brain) which in turn creates very strong memories. The same would hold true when comparing learning through reading and learning through a lecture.
However
This depends on many things:

For example if the lecturer is boring and monotone, it's the same or worse (boring lectures can put people to sleep) than giving a student something to read.

It also depends on the student's ability and motivation. If he or she is motivated and enjoys the subject, they will retain a lot of information from reading and working on their own due to their sense of joy in the subject--an emotional response will in turn encode memories more strongly.

Lastly it depends on how well the concept is explained. If a student does not understand a concept then for them to perform the calculations it will require a lot more memory work. If they understand something, then the actual memory work will be less, because they need not recall as much information in order to solve the problem.


In general though I would say that videos and lectures have more potential of creating memory retention due to providing more stimuli for the student.