The average undergraduate spends 80% of class time in lecture.
College students spend at least 10 hours per week listening to lectures. Based on a typical undergraduate course load, these lecture hours account for about 80% of class time. Notetaking is considered an essential skill to record lecture content.
Source: Anderson, T. H. & Armbruster, B. B. (1986). The value of taking notes (Reading Education Report No. 374). Champaign: University of Illinois at Urbana-Champaign, Center for the Study of Reading.