We have a choice, nay, a responsibility, to consider the long-term consequences of our choices, and this holds true in our choices as designers for learning practice as well as in other places.

Pedagogies vary. Some are more instructivist, talking about presenting concepts, examples, and then providing practice in sequence. Problem-based learning (PBL) and other similar approaches (e.g., case-based learning) take a different approach, having ill-structured (though carefully chosen) problems at the center, using learner initiative to a great extent, with instructors playing a facilitating role, and using the challenge to motivate attention to relevant concepts and examples.

Which choices lead to better retention over time and better ability to solve problems?

The question

Harold Barrows’ introduction of problem-based learning in 1986 (see References) sparked considerable interest and debate about this approach has continued to this day. Medical schools have gone as far as turning over their entire curriculum to PBL. Is this shift justified? In a notorious article in 2006, Kirshner, Sweller, and Clark took on constructivist approaches (including PBL) in general, arguing that minimal guidance fundamentally couldn’t work. Is this conclusion justified?

Overall, meta-analyses to date have been inconclusive about the effectiveness of PBL. Could a more refined analysis address this inadequacy, by asking a more refined question: when is PBL effective?

The study

Johannes Strobel and Angela van Barneveld decided to answer these questions. Using existing meta-analyses of PBL, they conducted a meta-synthesis of the reports, with a view towards answering the question, “What generalizable value statements about the effectiveness of PBL can be made and are supported by the majority of meta-analyses?”

The approach taken was specifically not a meta-meta-analysis but instead a meta-synthesis (the differences get into important issues but these are pin-dancing for most of us). The steps were to select relevant articles, translate them into common language, and integrate the findings.

Strobel and van Barneveld found eight meta-analyses that met their criteria, and they synthesized them. They divided up different types of outcomes to evaluate: outcomes on retention of knowledge over time, and on development of problem-solving skills.

The results

The results favored traditional classrooms for knowledge retention in the short-term. That is, if you are trying to pass tests shortly after the learning experience traditional approaches work best.

However, the results favored PBL for longer-term retention and long-term skill development. As a side benefit, both students and staff received PBL more positively.

The implications

While these results were largely from the education sector, the outcomes are clearly relevant for practitioners in other areas. It’s not surprising, frankly, that practice environments that focus on meaningful problems introduce cognitive gaps, or that support for learning-by-doing would lead to better skills in doing. This means, however, that we need to carefully examine the practice we set learners.

In short, practice for skill-development should:

  • Provide ill-structured, unsolved problems
  • Ensure those problems are meaningful to the learner
  • Support learners in interpreting and providing solutions
  • Facilitate discussion around the domain and the process

Strobel and van Barneveld’s concluding quote says it best: “PBL is significantly more effective than traditional instruction to train competent and skilled practitioners and to promote long-term retention of knowledge and skills acquired during the learning experience or training session.”


Barrows, H. S. “A Taxonomy of Problem-based Learning Methods.” Medical Education, 20, 6. 1986.

Kirschner, Paul A., John Sweller,  Richard E. Clark. “Why Minimal Guidance During Instruction Does Not Work: An Analysis of the Failure of Constructivist, Discovery, Problem-based, Experiential, and Inquiry-based Teaching.” Educational Psychologist, 41(2). 2006.

Strobel, J. & A. van Barneveld. “When is PBL More Effective? A Meta-synthesis of Meta-analyses Comparing PBL to Conventional Classrooms.” Interdisciplinary Journal of Problem-Based Learning, 3 (1). 2009. http://docs.lib.purdue.edu/ijpbl/vol3/iss1/4/