The Effect of Classroom Session Duration on Learning Retention

Someone asked about class session duration and retention rates. Since I am facilitating a session on “Re-Charging Classroom Training at the Learning 2009 conference next week, I thought I address this issue here.

I haven’t found many studies that deal directly with duration. Moreover, retention is more complicated than that. Consider the following:

1. A proxy for the duration question is the concept of attention span. There are some studies on this. Ruff and Lawson found that attention span varies roughly with age of the learner. This was for very young subjects, so extrapolation to adult learning has some risk. Subsequent rules of thumb derived from this finding say that attention span is 1-4 minutes per year. So a 30 year old adult learner might be able to focus attention from 30 minutes to two hours before some kind of break is required. It’s reasonable to assume that successive work-break cycles have diminishing returns.

2. There’s been a lot of good research by Clark, Nguyen, and Sweller on learning efficiency in the context of e-learning, but much of it can be applied to the classroom. Issues like cognitive load, segmenting, pacing, and practice are all relevant to classroom training. They may easily override concerns of duration of the session.

So assuming good presentation, pacing, and segmenting techniques are employed, and refreshing breaks are given, you may expect adequate efficent learning from 4,6, and 8 hour sessions for adult learners. This is supported to some extent by Schultz and Sharp’s study finding no difference between 50 minute and 75 minute classroom sessions.

However, if the content somehow requires concerted attention for an uniterrupted span, I would predict that learning efficiency would start to diminish after 30 minutes and drop off dramatically after two hours.

I think you’ll find most successful presenters and facilitators would agree with this. I plan to bring this question up at our session at Learning2009. Check this blog for the results


Development of sustained, focused attention in young children during free play. Ruff, Holly A.; Lawson, Katharine R. Developmental Psychology. Vol 26(1), Jan 1990, 85-93.

Efficiency in Learning by Clark, Nguyen, and Sweller. 2006. Pfeiffer. San Francisco, CA.

The Effect of Class Duration on Academic Performance and Attendance in an Introductory Computer Class. Leah A. Schultz and Jason H. Sharp. Proceedings of ISECON, 2007, v24.


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