lecture only when I am convinced it will do more good than harm.”
Because lecturing as an instructional technique can easily become non-learner-centered, it needs to be dealt with carefully. Lecturing can offer an effective way to facilitate learning. However, as a general rule lecturing seems to work most effectively in “punctuated blocks” lasting no more than fifteen minutes. Research supports this approach [Stuart & Rutherford, 1978 and Penner, 1984, as reported in Johnson, D.W., Johnson, R.T., & Smith, K.A. (1998). Active Learning: Cooperation in the College Classroom. Edina, MN: Interaction Book Company.], including this surprising finding: students recorded items in their notes concerning 41% of material given in a 15-minute lecture, 25% of material given in a 30-minute lecture, and only 20% of material in a 45-minute lecture. Because active learning produces better results than passive learning, we recommend you give lectures that last fifteen minutes or less before then move to a learning activity in which students discover/construct their own knowledge and meaning.