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Case and 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
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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 5th 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 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 3-6 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.
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)
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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 thousand 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?
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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.
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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 Research Academy 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 Refective
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.
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Some On-Line Resources:
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) http://www.udel.edu/pbl/
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. .
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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.
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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 Northwetern created problem-based honors workshops and invited students to participate in an experiment in problem-based
learning. They split the volunteers into comperable 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?
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