One way to answer that question is to ask an expert, and Clyde Freeman Herreid is a good expert to consult. Beginning in the late 1970s he (and various colleagues) started advocating the use of cases in the sciences. If you've been reading this newsletter for decades, you will find his work covered in some of our early issues. His work in this area has continued. He now directs the National Center for Case Study Teaching in Science (NCCSTS), which offers a website containing a collection of nearly 500 case studies, among other resources (http://sciencecases.lib.buffalo.edu). And those case studies are available, free of charge, for use in individual classrooms.
Herreid and colleagues have asked themselves the question raised in the title. To answer, they surveyed the more than 1,300 teachers on the Center's listserv (mostly biologists and faculty who teach health-related subjects), asking them to identify their favorite case and say what made it their favorite. “We thought it would be instructive to identify the faculty's special favorites on our website, but more important, to help us identify those characteristics that make a case good.” (p. 70)
Their article lists the top 20 cases, which aren't all that relevant unless you teach in the life sciences, but what respondents identified as the characteristics of those cases are useful to teachers who use case studies and especially to those who write (or consider writing) the ones they use.
First off, respondents said that the content was important. Whatever the case is about has to relate to what's being taught in the course. After that respondents made comments that pertain to the structure of the case—they liked the cases that were current, short, open-ended, user friendly, well organized, practical, lab oriented, and activity based. (p. 72) They gravitated toward cases that were realistic and relevant to students. The number one favorite case on the website deals with energy drinks and is cleverly titled, “A Can of Bull.”
Respondents also favored cases that promoted critical thinking and often that was equated with cases that emphasized the scientific method—cases that were designed like experiments, with “tests executed, evidence honored, assumptions examined and conclusions questioned.” (p. 72)
These teachers also made comments that pertain to the teaching method required by the case. They preferred cases that “disclose information to the students bit by bit.” (p. 73) This gives teachers control over the timing and tempo of case discussions. “Students working in small groups have the maximum opportunity to interact in collaborative teams, as the mystery unfolds.” (p. 73)
Herreid and colleagues note that when their work on science-based cases first started, they used a Harvard Business school typology of case characteristics. Based on the results of this survey, they tweaked that list only slightly. Here's the list, which they conclude with a comment about how cases should be written—“with exuberance, charm, and wit.” (p. 75)
A good case should 1) tell a story, 2) focus on an interest-arousing issue, 3) be current, 4) create empathy, 5) have dialogue, 6) be relevant, 7) serve a teaching function, 8) be conflict provoking, 9) have a dilemma to be solved, 10) have generality, and 11) be short.
That's a great set of criteria, whether you're writing a case or selecting one to use in your course.
Reference: Herreid, C.G., Schiller, N.A., Herreid, K.F., and Wright, C. (2012). My favorite case and what makes it so. Journal of College Science Teaching, 42 (2), 70-75.