Problem-based learning: panacea or cult?

Abstract

Comment from GroverIs problem-based learning (PBL) a panacea or a cult where belief prevails over evidence? The basic tenet of PBL is that it is a more efficient way of learning than lecture-based learning (LBL). However, there are no appropriate tools to measure learning. As scientists we do not conduct experiments without well-designed measurement tools. Yet, more schools are adopting PBL.In this issue of TiPS, Michel and colleagues [1xComparison of problem- and lecture-based pharmacology teaching. Michel, M.C et al. Trends Pharmacol. Sci. 2002; 23: 168–170Abstract | Full Text | Full Text PDF | PubMed | Scopus (42)See all References][1] report: ‘Thus, students participating in a pharmacology class involving both PBL and LBL elements reported that they had spent only ∼1 h in preparation for their lecture sessions but 3–4 h in preparation for each PBL session. These findings are consistent with a recent report on a PBL-based epidemiology course in which PBL students worked more steadily during the semester but spent only marginally more time on the course overall.’ However, no data are provided for how much time PBL and LBL students spend at the end of the semester. One can only conclude that preparation for a PBL session took the students 3–4 times longer than for LBL. Another statement in this article is that the tutor time is similar for PBL and LBL. This is hard to reconcile. The number of students and the actual time spent by the tutors preparing problems and administering the course are not provided. Would a scientific journal accept a pharmacology manuscript with such vague information?PBL, defined as small-group self learning, does take substantially longer than large-group LBL for the students and for the faculty. In the three-year MD program at McMaster University, pharmacology is an elective. I have offered pharmacology electives to students in their first, second and third year. An elective consists of 8–12 sessions each lasting 90 min. The first session starts with the discussion of goals and approaches to be taken. The students choose PBL, although they want me to be the resource person because self learning is too demanding on their time. We invariably end up with a hybrid system. The last 15 min of each session are spent on a problem. The next session starts with a 40–50-min lecture followed by a discussion of the previous problem and identification of issues in the next problem. More drug categories are covered in detail by groups about to complete the MD program. Here the students contribute more because they have heard of the drugs previously during the program.I also teach an LBL-based pharmacology course to 50–60 third- or fourth-year non-medical undergraduate students. Answering questions from lectures and assignments used to take 6–10 h per week of my time. PBL was introduced to entice the students to come to an extra 50-min PBL/discussion class where they could also ask questions. Students form small groups in the lecture theatre itself. A teaching assistant and I hop from group to group. In 20 min, issues in a short problem are discussed without trying to solve it. This leaves 25 min for questions about anything. Two lectures follow. In the next PBL/discussion class, 5 min are spent on the previous problem. There are three outcomes: (1) because most questions are answered in the class, only about ∼1 h each week is needed to answer more questions outside the classroom; (2) the number of questions the students ask in lectures has increased from 0–2 per lecture to 4–6 per lecture; and (3) the number of students volunteering to answer questions posed in the class has similarly increased. The course also contains six open-ended problems for group discussion with no marks associated with them. 30–40% of students do not come to these classes. End-of-the-year discussions about the course consistently show that a similar percentage feel this part of the course to be the most enjoyable. Even this limited use of PBL has made the students more pro-active (outcomes 2 and 3 above).In conclusion, PBL can be used to obtain more pro-active graduates. However, PBL as a more efficient way of learning is supported by the faithful without any credible evidence.