Related psychological research has shown that it takes 16 hours of lessons to change behavior, on average. Thus, one eight-hour class is often not sufficient, if behavior change is the goal.
Seemingly similar classes may vary in length. It can depend on:
- What is covered
- In how much depth material is covered
- How much interaction occurs between the instructor and student
- The delivery format (lecture versus discussion and interaction)
Among adult learners the opportunity to interact and participate has been shown to be very important for attention and material retention. One needs to think through just what one hopes a class will deliver. With experience, it will be easier to decide the importance of format, attention span, the role of accompanying material, the quality of the instructor, the need for participation, and the like. These factors may vary in importance with the material and the students involved.