A Newsletter of the Center for Teaching Effectiveness
January 1995

Problem-Based Learning in Physics:

The Power of Students Teaching Students

Barbara J. Duch
Center for Teaching Effectiveness

One week you are a health care worker in the Winter Olympics at Lilihammer. The top French ski jumper has fallen and injured his hip. What do you tell him to do in order to minimize the forces on the sore hip? Another week you are a traffic officer investigating an automobile accident involving personal injuries. What measurements do you take, what data do you need to gather, and what assumptions do you need to make in order to discover which driver is at fault? How will you prove that you are right? You most likely will be required to testify in court.

These are a few of the many roles played by students in my Honor's General Physics course as they attempt to solve complex, real world problems using physics principles. The problems developed for this class demanded that students do several things: connect new knowledge to old; recognize what they know and understand -- and what they don't; learn concepts thoroughly enough so they can explain and teach in their own words.

In a traditional science class, learning tends to proceed from the abstract to the concrete, with concepts being introduced first, followed by an application problem. In problem-based learning (PBL), students are presented with an interesting, relevant problem "up front", so that they can experience for themselves the process of doing science: they proceed from the known to the unknown in order to understand the underlying abstract principles. Students who acquire scientific knowledge in the context in which it will be used are more likely to retain what they learned, and apply that knowledge appropriately (Albanese and Mitchell, 1993; Boud and Felletti, 1991).

Students worked in groups of four and learned to teach each other, effectively communicating what they knew -- and what they didn't. They learned to depend on each other in order to successfully solve complex problems, and to design and carry out open-ended experiments. Research has shown that students' achievement is enhanced when they work together in a cooperative learning environment (Johnson, et al.,1991; Bonwell and Eisen, 1991). Use of cooperative groups fosters the development of learning communities in the classroom which reduces the high competitiveness and isolation of typical science courses (Tobias, 1990 and 1992; Project Kaleidoscope, 1991).

Features of this coures

I randomly assigned the twenty-four students to six permanent groups of four. Each individual in the group had specific responsibilities each week, with these roles (discussion leader, recorder, reporter, focusser/accuracy coach) rotating weekly. Each group also established a set of groundrules and consequences under which the group functioned. Most groups adapted groundrules of the following type: mandatory attendance at class and group meetings; come prepared to class and group meetings, reporter must show rough draft of problem/lab one day before assignment is due; etc. Students in their assigned groups worked through the real world problems, teaching each other the physics principles needed to understand the problem. Some problem sets were assigned to the groups while some were done individually. Experiments were also designed to be conducted in groups of four.

Real World Applications

Whenever possible, problems and experiments related the basic physics principles to the real world -- especially biology, medicine and the human body. For example, while a traditional physics class learns about forces and torques using weights, bars, and pulleys, I challenged my students to discover how those concepts could be applied to determine how to minimize force on the injured hip of an Olympic ski jumper. They found that if the center of mass was shifted more directly over the injured hip the forces were minimized.

While a traditional class learns about linear momentum, my students were analyzing the description and sketch of a police automobile accident report. And using every concept learned in the course up until that time (equations of motions, Newton's Laws, work and energy principles and conservation of momentum in two dimensions), the students had to make assumptions (and justify them) in order to decide fault in the case.

Student Attitudes

Student response to various aspects of this course on final course ratings forms was quite positive. When students were interviewed by an independent consultant, they all responded that working in groups aided their learning.

Here are some typical comments:

Responding to the question: What did you learn that was new and meaningful to you?

Responding to the use of complex real world problems to initiate the learning of physics principles, students responded:

Personal Observations

Using problem-based learning, with students responsible for working and learning together in groups, I found that attendance was almost 100%, students were active, participating and questioning thoughout class. They continually challenged me with questions which went beyond typical basic physics principles. Would I return to lecturing in a traditional fashion? Not a chance. The excitement and energy of a room of students working in groups, teaching each other, challenging each other, and questioning each other is what I'll always want to see in my classroom.


This article is adapted from a larger paper submitted to the Journal of College Science Teaching.

Last updated Feb. 20, 1997.
Copyright Barbara Duch, Univ. of Delaware, 1995.