What is the longest period of time a student can focus on a lesson without his/her mind wandering?
Probably 15 to 20 minutes, max.
I sat in the back of the classroom, observing and taking careful notes as usual. The class had started at 1:00 o’clock. The student sitting in front of me took copious notes until 1:20. Then he just nodded off. The student sat motionless, with eyes shut for about a minute and a half, pen still poised. Then he awoke, and continued his rapid note–taking as if he hadn’t missed a beat.
Adult learners can keep tuned in to a lecture for no more than 15 to 20 minutes at a time, and this at the beginning of the class. In 1976, A. H. Johnstone and F. Percival observed students in over 90 lectures, with twelve different lecturers, recording breaks in student attention. They identified a general pattern: After three to five minutes of “settling down” at the start of class, one study found that “the next lapse of attention usually occurred some 10 to 18 minutes later, and as the lecture proceeded the attention span became shorter and often fell to three or four minutes towards the end of a standard lecture” (pp. 49–50).
This makes sense to me.
I think a lot of teachers intuitively deal with the fact that student attention waxes and wanes by a) repeating points, b) asking multiple questions (which repeats points), and c) using the blackboard/whiteboard (also repeats points).
That’s why Powerpoints are a problem: if you miss a slide you’re sunk. Nothing stays on the board.