I do remember college professors who would stop the lecture for a few seconds and then say “this is important” and then resume the lecture.
That was a “clue” that at some point there would be an exam question on that point.
Of course that only helped if you attended class and managed to stay awake during class.
;-)
Dad went through OCS in 1968—the instructors had a bell that they would ring, which helped those struggling to stay awake.