How much is too much?
How much should we be “covering” in class?

The challenge of how much of a subject to cover in class is a faculty member’s constant dilemma. Russell, Hendricson and Herbert suggest that less is really more when it comes to learning.

Concerned about the explosion of information available in medical texts and the perception of lecturers that they must cover even more material in the limited time available, the authors studied the effect of information density on student retention. They prepared three different lectures on the same subject. Ninety percent of the sentences in the high-density lecture disseminated new information. By comparison, only 70 percent of the medium- and 50 percent of the low-density lecture presented new information. During the remaining time, the lecturer reinforced material by restating key ideas, highlighting the material’s significance, providing illustrative examples, and relating the material to the student’s prior experience. The lectures were presented to a total of 123 students randomly distributed into three groups, which showed no significant difference in cumulative GPAs. Finally, students were given a pretest that showed no significant difference in their knowledge base, a posttest immediately after the lecture, and an unannounced posttest 15 days later.

Statistical results clearly showed that students in this study learned and retained lecture information better when the density of new material was low. The implication is that the amount of new information that students can learn in a given time is limited and that we defeat our purposes when we exceed that limit. [Who among us has not gone over the allotted class time by a minute or two to provide “just one more thing”?] This study suggests, however, that we would be better off presenting only the basic material necessary to achieve our learning objectives: approximately only 50 percent of the material presented in any lecture should be new. The rest of class time should be devoted to material or activities designed to reinforce the material in students’ minds.

This study is significant since one of the chief barriers presented by faculty to using active learning is that “there is simply too much content to cover.” Apparently less new content and more time reinforcing the facts and concepts presented [which could include active learning] will lead to greater student learning.

Full citation for this article:
Russell, I. J., W. D. Hendricson, and R. J. Herbert. November, 1984. Effects of lecture information density on medical student achievement. Journal of Medical Education 59: 881–889.