Problem-Based Learning

The case method of teaching, developed originally for use in business and professional schools, has become an increasingly popular teaching strategy in courses from all disciplines. Creating case-based courses or units involves identifying situations or creating realistic scenarios in which students will have to use the relevant intellectual skills and the appropriate facts from the discipline to analyze successfully the scenario and recommend some course of action. Problem-based learning (PBL) emerged primarily in medical schools to confront a disturbing reality: Students could memorize extensively without any sufficient change in their ability to use the information to diagnose diseases. The basic approach is to use authentic problems to engage students in the subject matter and to help develop effective critical thinking, communication and social skills. The skills and information that form the learning objectives are embedded in authentic and intrinsically interesting problems that will arouse curiosity and challenge students to rethink their assumptions and examine their mental models of reality. In the best of cases or problem-based courses, students face challenging problems but in a safe environment in which they can grapple with those problems collaboratively, come up short, receive feedback and try again. Students learn to analyze complex problems and how to perform the necessary research to confront the problems or test their proposed solutions.

Example of A Case – Used in History

The United States and Jewish Refugees After the Holocaust

In the spring of 1945, the ghastly extent of Nazi atrocities became visible as Allied armies liberated German concentration camps. The haunting scenes of human carcasses stacked in the dumps of Buchenwald, Auschwitz and Bergen-Belsen morbidly confirmed earlier rumors of fascist brutality.

In July, President Harry Truman saw the misery of war firsthand during his trip to Potsdam (outside Berlin) to meet with Stalin and the British. As the presidential motorcade sped along the road from Antwerp to Brussels, Belgium, Adolph Hitler’s legacy rolled past the window in a panorama of destruction and horror. Bombed-out homes and factories, a Nazi concentration camp at Breendock, and seemingly endless lines of refugees punctuated the drab panorama. In Brussels, the president boarded his plane for the flight to the heart of the defeated Third Reich. Scenes of rubble appeared everywhere. Over the cities of Kassel and Magdeburg, a military aide later wrote, “we could not see a single house that was left standing.”

Problem-based learning has as its organizing center the ill-structured problem, which…

  • is messy and complex in nature
  • requires inquiry, information-gathering and reflection
  • is changing and tentative
  • has no simple, fixed, formulaic, “right” solution

Source: Center for Problem Based Learning

When the president arrived in Germany, he took a two-hour drive that revealed even greater destruction. “Every building we saw was either badly damaged or completely destroyed,” an aide reported. “Much more distressing,” one advisor told his diary, “was a long procession of old men, women, children, marching in great numbers along the country roads.” They were “carrying, pushing or pulling what was left of their belongings,” Truman added.

Jewish refugees faced special problems. Several hundred thousand bitter, cynical and homeless survivors of the Holocaust had escaped the death chambers but languished in concentration camps at war’s end. Harried and uprooted, many existed for months after Hitler’s death in barbed-wire-enclosed holes, unsanitary barracks, still wearing uniforms taken from dead German soldiers or, worse, Nazi-issued prison outfits.

Fall and winter news from Europe said that many who escaped the Holocaust now faced an unhappy future of more pogroms and discriminations. A new wave of uprooted, the belated victims of prejudice, inundated the already flooded streams of humanity pouring across the continent from Poland to France–tens, hundreds, thousands gushing into U.S. and British hands, drowning hopes that Nazi defeat would purify the Old World. Death, depression, pessimism, stench, hunger, disease, suicide, insanity–like a festering sore the elements of life for surviving Jews marred the joys of victory.

What could President Truman do, if anything, to relieve this misery? Could he bring some of these refugees to the United States? Or send them to other countries? Many of the surviving Jews, tired of mistreatment and impressed with Zionist promises, sought entrance to Palestine. Should Truman support their desires? Many people in that country opposed such moves, and already violence plagued this Holy Land.

[ Twenty-two pages of background to the conflict in Palestine, the rise of the Zionist movement, US policies toward the Middle East, U.S. Refugee policy, British Mandate policies, etc.]

What to Do?

In 1946 President Truman sought advice from two commissions. How would you advise him? What understanding of this history justifies and explains your advice?

Appendix: This case is done in class as a simulation, with different groups or individuals responsible for researching and playing different groups or individuals, including William H. Stringer; John Lewis; Anglo-American Committee of Inquiry (1946); Lessing J. Rosenwald; Major General John H. Hilldring, Assistant Secretary of State for occupied areas; Princeton University philosopher W. T. Stace; Arab leaders, including the king of Saudi Arabia; Loy Henderson and others in the State Department; Paul L. Hanna; A. H. Silver; Stephen Wise; Harry Truman; British diplomats and political leaders; and executives of oil companies with major holdings in the Middle East.

This case is based, in part, on Kenneth R. Bain, The March to Zion; United States Policy and the Founding of Israel, College Station: Texas A&M University Press, 1979, and Kenneth R. Bain, The Last Journey Home: Franklin Roosevelt and the Middle East (forthcoming).

Problem-Based Learning Case Studies

by Clyde Freeman Herreid, Distinguished Teaching Professor, Biological Sciences Department, SUNY Buffalo

Problem-based learning (PBL), as a method of instruction, took root at McMaster University’s medical school in the late 1960s. Today it is used by 22 medical schools in North America as well as Australia, Israel and the Netherlands (Mayo, Donnelly and Schwartz, 1995). An extensive review of its strengths and weaknesses has been written by Albanese and Mitchell (1993). Its use in basic science programs is just beginning and is spearheaded by the University of Delaware, which just recently held its fifth annual international conference. An example of its use in a physics course was published by Duch (1996).

There is rich literature about PBL and the various skills that are needed to be successful. What is missing are the PBL problems. The literature holds few case examples that can be passed along to other instructors (e.g., an exception being Rangachari’s 1991 article on PBL in an undergraduate course in pharmacology). We are a long way from achieving the bank of cases developed for business at places like Harvard. Hence, every case helps. Below, I give a PBL case approach using the controversy over HIV and AIDS.

The topic of acquired immunodeficiency syndrome, AIDS, is ideal for case study teaching. The topic is complex, important, controversial, and has public policy implications. It is of vital interest, and in every course where I have used case studies, those cases involved with AIDS always receive the highest marks from students. Over the past ten years, the scientific community has been alternately challenged, irritated, frustrated and bemused by Dr. Peter Duesberg of the University of California at Berkeley, and his position on AIDS. Duesberg, a renowned virologist and a member of the prestigious National Academy of Science, does not believe that HIV causes AIDS. Rather, he claims that AIDS is the result of recreational and anti-HIV drugs. Virtually all scientists who have studied the issue believe Duesberg’s opinions to be extreme, although some maintain that HIV is not the sole cause of AIDS. A December 9, 1995, issue of Science devoted an eight-page special report on “The Duesberg Phenomenon.” Nevertheless, Duesberg believes his views have not received the attention they deserve and his research program has been seriously affected because of his unpopular position. He has not received any grant support since becoming embroiled in the controversy according to reports in The Scientist (March 20, 1995). In that publication, he is quoted in explaining why the AIDS community has rejected his views and why he can’t get funded for research:

“A whole generation of AIDS scientists, retrovirologists – in the last 10 years their names, their papers, not to mention their fortunes, solely and exclusively rest on one thing, on HIV. If HIV is not what it is said to be…all these people…would be nobody… In fact, worse than that: Many would be rightfully blamed for having intoxicated 200,000 Americans with AZT every six hours and panicked millions of people with a positive AIDS test…They would have done unbelievable harm in the name of this hypothesis if this hypothesis were proven wrong. So these people cannot afford in the least bit to consider an alternative that might end their careers.”

Student Assignment

The following assignment is basically that which is used by practitioners of problem-based learning. As I have outlined above, the case requires part of three class periods. It involves the use of papers from the literature rather than a written scenario. I have used it for groups of three to six students working in permanent groups without tutors with reasonable success. Basically, I give the groups sets of papers and ask them to identify the learning issues and to educate themselves about AIDS.

I give out two 1988 Science magazine articles: a short critique by Duesberg entitled “HIV is Not the Cause of AIDS,” and an adjoining article: “HIV Causes AIDS,” by noted experts Drs. W. Blattner, R.C. Gallo, and H.M. Temin. I also include copies of their rebuttals to one another.

On Day One, the students’ basic task is to identify the issues that are important in the papers, as well as to identify the terms, concepts and information they need in order to resolve the problem as they see it. Then the students subdivide the workload, and after class go to the library, the Internet and their texts to try and resolve their questions.

On Day Two of this case, the students pool their information and summarize their knowledge. To aid the process, I give them a couple of additional papers to be sure that certain points are addressed. For example, Duesberg’s (1991) article highlights his views especially well. Also, Moore’s (1996) review of Duesberg’s book Inventing the AIDS Virus is useful, as is the Scientific American (1995) article on “How HIV Defeats the Immune System” by Nowak and McMichael.

With these papers in hand, the students are asked to again identify any new issues, terms and information they need. Once again they set out and collect the information for the next class.

On Day Three of the case, the students pool their information for the last time and prepare to deal with the final assignment. In their groups, I ask them to evaluate the nine points that Duesberg made in his original Science article where he claimed “HIV is not the cause of AIDS because it fails to meet the postulates of Koch and Henle, as well as six cardinal rules of virology.” In class, the groups write brief summaries about each of the nine points in light of our most recent information.

This case comes from the University at Buffalo Case Studies in Science Web site and is reprinted with permission. References available at the University of Buffalo Library.

PBL promotes:

  • Motivation 
    PBL makes students more engaged in learning because they are hard-wired to respond to dissonance and because they feel they are empowered to have an impact on the outcome of the investigation.
  • Relevance And Context 
    PBL offers students an obvious answer to the question, “Why do we need to learn this information?”
  • Higher-Order Thinking
    The ill-structured problem scenario calls forth critical and creative thinking by suspending the guessing game of, “What’s the right answer the teacher wants me to find?”
  • Learning How To Learn 
    PBL promotes metacognition and self-regulated learning by asking students to generate their own strategies for problem definition, information gathering, data analysis, and hypothesis-building and testing, comparing these strategies against and sharing them with other students’ and mentors’ strategies.
  • Authenticity 
    PBL engages students in learning information in ways that are similar to the ways in which it will be recalled and employed in future situations and assesses learning in ways which demonstrate understanding and not mere acquisition. (Gick and Holyoak,1983)

Source: Center for Problem Based Learning

A Case in Biochemical Evolution: Dating Eve

Written by Harold B. White, Professor of Chemistry and Biochemistry, University of Delaware. Reprinted by permission.

Allan C. Wilson (1934-1991), perhaps the foremost molecular evolutionist in recent time (1-3), never shied from controversy. His lifelong interest in natural history and biological evolution gave him the uncanny ability to identify the unresolved, controversial issues of phylogeny and evolutionary theory that he and his associates could address with modern biochemical techniques (4-18). Repeatedly he confronted biologists and anthropologists with data that challenged their cherished models. For his work he received a MacArthur Foundation fellowship, dubbed the “Genius Award” because the recipients are often outstanding but unconventional thinkers from diverse fields (19). He was a member of the American Academy of Arts and Sciences and the Royal Society of London.

In 1987 Wilson and coworkers Rebecca Cahn and Mark Stoneking claimed they had evidence that the most recent common ancestor of all modern humans was a woman living in Africa about 200,000 years ago (20). They based their conclusion on the analysis of restriction maps of mitochondrial DNA taken from 147 individuals representing different races and geographic origins. Their methods and results elaborated and supported earlier and continuing work in Cavalli-Sforza’s lab (21,22). In typical journalistic fashion, the popular press immediately hyped this as the “Eve Hypothesis,” “Garden of Eden Hypothesis,” or the “Out-of-Africa Hypothesis.”

In the subsequent years Wilson and his coworkers continued to collect data to test the “Eve Hypothesis.” They sequenced particular segments of mitochondrial DNA from over 200 individuals (23,24), and their conclusions remained consistent. In addition, another group using restriction mapping of mitochondrial DNA from 3065 humans also concluded that humans had a recent origin in Africa although they refused to set a date (25). Thus, in 1991 when Allan Wilson died while being treated for leukemia, there seemed to be consistency in the results and growing support for his conclusions (26).

For Group Discussion

What would you want to know in order to evaluate the claims of Wilson and his challengers?

Assignment for Next Class

Locate and read reference 20. Be prepared to explain what was done and discuss the basis for the conclusions in class. It is important that you understand reference 20 before you go on to subsequent assignments in this case study.

At the time of his death, Wilson’s hypothesis that all living humans had a common maternal ancestor who lived in Africa as recently as 200,000 years ago was gaining wide acceptance. This appeared to be a second major scientific victory for him. In 1967, he and Vincent Sarich (6) shook the human family tree when they claimed, based on immunological comparisons of serum albumens, that humans, chimpanzees and gorillas had a common ancestor five million years ago. At the time paleoanthropologists, who had settled on a common ancestor about fifteen million years ago, resented and challenged the invasion of their domain by outsiders. Nevertheless, most anthropologists now accept times of five to eight million years ago. Similarly, Wilson’s “Eve Hypothesis” (20,24) was challenged by some paleoanthropologists who would have accepted a common human ancestor closer to one million years ago (27,28). Other paleoanthropologists agreed with Wilson’s conclusions (29).

During the past quarter-century, powerful computers have been developed, and computer programs for constructing trees based on homologous DNA and protein sequences have become rather sophisticated (30-32). As a consequence, most people who use them do not fully appreciate their limitations. Some researchers (33) thought that Wilson’s group (20) had overinterpreted their data. Although Wilson’s next major paper in the area (24) was published posthumously, reverence for him did not inhibit a full-scale challenge of his methodology (34-39) that elicited a partial retraction by a coauthor (40). While the original data are good, his reanalysis shows that the “Out of Africa” model is somewhat weakened, but not rejected, and the “dating of Eve” not strongly challenged (41,42).

Assignment for the following two classes

There are a number of issues that emerge from Wilson’s work and the challenges to it. . .

a. Wilson’s conclusions relate only to the most recent maternal ancestor of all humans. There were many other women living at that time who are also our ancestors. Explain. Is it possible that the most recent paternal ancestor lived over a million years ago (43)?

b. There are a variety of ways to construct phylogenetic trees from sequence data. Because there must be a single phylogeny, why do the various methods sometimes give different answers, none of which may be the true phylogeny? Would the phylogeny be affected if nuclear DNA sequences were used (44)?

c. What can the fossil record tell us about our most recent common ancestor? Is it possible for both the paleoanthropologists and the molecular evolutionists to be correct?


See Dating Eve: A Case Study in Biochemical Evolution

ALTHOUGH the case method has been used for years to teach law, business, and medicine, it is not common in science. Yet the use of case studies holds great promise as a pedagogical technique for teaching science, particularly to undergraduates, because it humanizes science and well illustrates scientific methodology and values. It develops students’ skills in group learning, speaking, and critical thinking, and since many of the best cases are based on contemporary–and often contentious–science problems that students encounter in the news (such as human cloning), the use of cases in the classroom makes science relevant.

Source: Case Studies in Science, State University of New York at Buffalo

A Bibliography on Teaching and Learning with Cases and Problem-Based Learning (PBL)

The literature on teaching with cases or problems is extensive. We include here only a small sample of that literature. For copies of a longer bibliography, call the Office for Faculty Advancement at 973-655-3276.

Albanese MA and Mitchell S. (1993). Problem-based learning: a review of literature on its outcomes and implementation issues. Academic Medicine, 68(1): 52-81.

Allen, D.E., B.J. Duch, and S.E. Groh. (1996). The power of problem-based learning in teaching science courses. Bringing problem-based learning to higher education: Theory and practice. LuAnn Wilkerson and W.H. Gijselaers, editors. San Francisco: Jossey-Bass Pub., 1996: 43-52.

Baron, J. (1981). Reflective thinking as a goal of education. Intelligence, 5, 291-309.

Barrows, H.S. (l986). A Taxonomy of Problem-based Learning Methods. Medical Education, 20, 481-6.

Benware, Carl A., Dice, Edward. (l984). Quality of Learning With an Active Versus Passive Motivational Set. American Education Research Journal, 21 (4), 755-765.

Boehrer, J. (1994). On teaching a case. International Studies Notes 19:13-19.

Bransford, John D. et al. (1990). Anchored Instruction: Why We Need it and How Technology Can Help. Cognition, Education, And Multimedia. Hillsdale, NJ: Erlbaum Associates.

Cliff, W.H., and A.W. Wright. (1996). Directed case study method for teaching human anatomy and physiology. Advances in Physiology Education 15: Sl9-S28.

Frederiksen, N. (l984). Implications of cognitive theory for instruction in problem solving. Review of Educational Research, 54(3), 363-407.

Herreid, C.F. (1994). Journal articles as case studies: The New England Journal of Medicine on breast cancer. Journal of College Science Teaching 3:349-355.

Hutchings, P. (1993). Using Cases to Improve College Teaching: A Guide to a More Reflective Practice . American Association for Higher Education. Washington, DC.

Lantz, J.M., and Walczak, M.M. 1997. The Elements of a chemistry case: Teaching chemistry using the case discussion method. The Chemical Educator: 1(6)

McKinley, C.J., and W.R. Stoll. (1994). A method of improving student learning in physiology: the small group workshop.American Journal of Physiology 11: S16-S23.

Seltzer, S., S. Hilbert, J. Maceli, E. Robinson, and D. Schwartz. (1996). An active approach to calculus. Bringing problem-based learning to higher education: Theory and practice. LuAnn Wilkerson and W.H. Gijselaers, editors. San Francisco: Jossey-Bass Pub., 1996. pp. 63-71. pp. 83-90.

Vernon, D.T.A. and R.L. Blake. (1993). Does problem-based learning work? A meta-analysis of evaluative research. Academic Medicine, 68(7): 550-563.

Three ways to learn more

Workshop on Teaching with Problem Based Learning, Institute for Transforming Undergraduate Education University of Delaware. Newark, Delaware. The Institute received the Theodore M. Hesburgh Award For Faculty Development to Enhance Undergraduate Teaching and Learning Certificate of Excellence for 1999.

Case Studies in Science Workshop, SUNY Buffalo, sponsored by the National Science Foundation.

Using Cases Effectively To Improve Learning and Teaching, A Working Conference for College Faculty, University of British Columbia, Vancouver, BC, conducted by Rita Silverman and William Welty.

Some Online Resources:

Case Studies in Science, maintained by Professor Clyde Herreid at State University of New York at Buffalo Case Studies in Science, State University of New York at Buffalo

Problem Based Learning, maintained by the Institute for Transforming Undergraduate Education at the University of Delaware (Recipient of the 1999 Theodore M. Hesburgh Award For Faculty Development to Enhance Undergraduate Teaching and Learning Certificate of Excellence) Problem-Based Learning at University of Delaware

Pew Case Studies in International Affairs, Enhancing Education in International Affairs, maintained by the School of Foreign Service, Georgetown University Pew Case Studies, The School of Foreign Service, Georgetown

Center for Problem Based Learning, maintained by the Illinois Math and Science Academy Center for Problem Based Learning

Essentially, international affairs cases are instructive stories: concise retellings of pivotal events in international relations, key foreign policy decisions, important trade negotiations and economic decisions, historical turning points, legal disputes and decisions, large- and small-scale development efforts, ethical dilemmas, and environmental quandaries.

Decision-forcing cases tell the story up to a point where the situation calls for action, leaving students to analyze the problem, weigh options and make a decision. Retrospective cases tell the whole story including the decision and its consequences, inviting students to analyze what happened, explore alternatives and draw conclusions. Both types provide significant factual information and insight into how actors and institutions function in the real world, as well as grist for considering persistent issues and productive exercise in analysis and problem-solving.

Case discussions are animated by immediate questions. Wrestling with the immediate questions invokes larger ones that extend beyond the case itself. Cases ground the abstract questions in specific events, which take meaning from the abstract questions–a synergy that enhances the power of case discussion as a learning process.

Source: John Boehrer, Director, Pew Faculty Fellowship

The Internet Classroom Assistant (Nicenet) offers an opportunity to build a collaborative, problem-solving environment using the Internet. It requires no special software and utilizes a simple Web browser such as Netscape. You can create conferences, post schedules, exchange documents, send personal messages, and so forth, all within a browser. Go to Internet Classroom Assistant for more information.

Problem-Based Learning in a Biology Course

In 1997, faculty members in the team-taught year-long sophomore survey course in biology at Northwestern created problem-based honors workshops and invited students to participate in an experiment in problem-based learning. They split the volunteers into comparable groups, allowing one to participate, keeping the other one out, and creating matched pairs between the two groups. The participants joined weekly workshops that met outside of class for two hours each week. In the workshops, teams of five to six students worked with undergraduate facilitators to tackle advanced problems in the discipline. The experiment worked so well (the performance of participants far exceeded that of comparable non-participants in the class) that the department turned the experiment into a program that in the fall of 2001 attracted nearly two-thirds of the students in this class of more than three hundred. Other science departments, including chemistry and physics, were so impressed with the results that they initiated similar programs in their gate-way classes, with equally impressive results.

Along the way, the faculty discovered something quite significant: the experience worked most effectively when students confronted authentic problems, the kind of problems that a scientist in the field might confront, rather than “school” problems that required little more than recall.

For Example

In the examples below, the first problem is something that will occur in the everyday life of some families, and its solution requires that the students use the principles of inheritance and the transmission of genetic information from one generation to the next. Most important, it allows the discussion of these principles and their application to the problem.

The second problem tests important principles of cell biology and of cancer biology that will also affect many families. However, the structure of the question is not as amenable to discussion of principles as is the first problem. The fact that the second problem tests a wider range of principles may make it more appealing for some to use as an exam question, but its structure limits its usefulness as a honors workshop question.

1. Todd and Sara wish to wed but are unaware that they share a common great-great-grandmother, who was heterozygous for a rare autosomal recessive disease. Given the following family structure (not included here), what is the probability that their first child will be affected?

2. How are cancer cells different than normal cells? What is an oncogene and what role do they normally play? What can happen to oncogenes when exposed to excessive UV light or carcinogens? What characteristic of cancer cells causes their spread throughout the body?