Renowned virologist and member of the prestigious National Academy of Science, Peter Duesberg has argued that AIDS is not caused by HIV, but is the result of recreational and anti-HIV drugs. In this PBL case, students read Duesberg's 1999 article in Science magazine titled "HIV is Not the Cause of AIDS" as well as a response to it titled "HIV Causes AIDS" by medical researchers Dr. William A. Blattner and colleagues. Students work in groups to identify the issues as well as any terms or concepts they don't understand, then research these out of class to pool their information as they learn about AIDS and HIV.

Intelligent Design continues to be a hot political and educational topic in some parts of the country. This discussion case study uses the dramatic setting of a public school board as it considers whether district science teachers should be made to read a statement to their classes identifying Intelligent Design as a competing theory to evolution that is worthy of scientific consideration. The relevant statement is in fact the one that was at the center of the 2004 controversy in Dover, Pennsylvania. This case would be appropriate in general biology or advanced courses where the focus is on evolution.

This case study presents a fictitious bio-terrorist plan to release anthrax in the United States. Students are assigned character roles and, through research, role-playing, and teamwork, develop a plan to minimize or avert the attack. The case is appropriate for courses designed for health professionals, general biology courses, and social science courses.

This case study was inspired by a successful lawsuit brought by students against a professor at Pace University who had assigned them the task of calculating the cost of a single aluminum atom in a roll of aluminum foil. The case deals with the concepts of Avogadro's number and the mole, and so would be relevant to nearly all introductory level science courses including chemistry courses for non-science majors, general science courses, and, perhaps, some introductory level biology courses in addition to general chemistry.

The ethics of human experimentation are explored in this case about the infamous syphilis studies performed at the Tuskegee Institute from the 1930s to the 1960s. Sponosred by the U.S. Public Health Service, 399 African American men with syphilis were recruited for a research study on the progression of the disease when left untreated. The case examines the science underlying the experiment as well as the ethical and racial issues. One of its goals is to help students understand the evolution in our thinking on issues of science, human experimentation, and race, and how they are conditioned by our culture. The case could be used in any course that explores the ethics of science.

This discussion case explores the scientific process involved in implementing an animal model in the study of Alzheimer's disease. Students read a short paragraph describing a study in which the brains of "trained" mice were injected with beta-amyloid fragments, which subsequently caused them to forget their tasks. The paragraph is a very short New York Times story reporting on an experimental study originally published in the Proceedings of the National Academy of Sciences. Based on the short description provided, students are asked to identify relevant components of the scientific method (problem, method, results, and conclusions). The case is suitable for a wide variety of science majors and non-majors courses.

Colony Collapse Disorder (CCD) has claimed approximately one-third of the commercial honeybee population in recent years. A number of causes have been suggested for this phenomenon, including the consumption of high fructose corn syrup (HFCS) by the bees. This directed case investigates the issues and chemistry that might be involved in CCD related to HFCS. The case was developed for use in an undergraduate organic chemistry or food chemistry course.

In this case study, students analyze a scientific study, first by analyzing news articles reporting on the research and then by reading the original research article. In working through the case, students identify the basic elements of a scientific study; evaluate the study and offer suggestions for improvement; analyze the appropriateness of the headlines of news articles in relation to their content; and compare the accuracy of information offered to the public in a news article with the information presented in a scientific paper. Designed for an introductory course in biological sciences for non-majors, the case could be used in any course that includes the study of the scientific method as well as in a scientific journalism course.

This case describes the pioneering work of Ignaz Semmelweis and his efforts to remedy the problem of childbed fever in mid-19th century Europe. Its purpose is to teach students about the scientific method by "dissecting" the various steps involved in this important, historical medical breakthrough. The case is an interrupted case, that is, students receive only one piece of information at a time, followed by discussion, before moving on to the next piece of information to solve the mystery.

The Cleaver family of television fame faces a dilemma-whether or not to clone their recently deceased dog Spot. Written for a high school introductory biology class, the case provides students with an opportunity to discuss animal cloning and its ethical implications. Students role-play the viewpoints of the father and mother, Jack and Grace Cleaver, and their son Ralphy as well as the dog Spot and debate the various positions on cloning.

Does an ice cube melt more quickly in salt water or in freshwater? The answer surprises the group of student science teachers portrayed in this case study. To explain the phenomenon they must figure out the interactions between two clusters of concepts: (1) density and its relationship to floating or sinking, and (2) three modes of heat or energy transfer due to a temperature difference (particularly conduction and convection, with an optional discussion of radiation). The case can be adapted for use in general education science courses or for introductory physics or chemistry courses.

This role-playing case on climate change policy is designed to engage student groups in parallel discussions on policy instruments and packages for controlling greenhouse gas emissions. Specifically, student groups discuss cap-and-trade and carbon tax policies for reducing carbon dioxide emissions. Each group has four students representing one of the following characters: climate scientist, economist, political sociologist, and the staff expert on science related policy. Students study the policies from a holistic perspective and explore related social, economic and environmental issues. In the end, each group drafts a statement for the senator that includes choices and recommendations based on these different views. This case is appropriate for introductory environmental studies and environmental economics courses once students have been introduced to the basic technical and scientific information on climate change.

This interrupted case engages students in issues contributing to the increase of dengue fever in Jamaica. The overall goal of the case is to make clear the connections between land use management and public health, specifically dengue fever. Students learn about the effects of land use management on the breeding of the Aedes aegypti mosquito and its implications for public health as well as about the spread, extent, and form of the disease. In addition, students are challenged to think of solutions to public health problems given limited resources (in terms of personnel and money). The case was created for an introductory course in fisheries, wildlife and conservation biology. It may also be appropriate for introductory biology and ecology courses. A PowerPoint presentation to supplement the case is also available.

This "clicker case" teaches students about the scientific method by following the story of the discovery of the cause of human gastric ulcers by two Australian biomedical scientists. Students see how the researchers followed up an unusual observation by applying the steps of the scientific method in support of their new hypothesis for the cause of this disease. Students practice the scientific method themselves by proposing their own hypotheses, identifying methods for testing the hypotheses, and predicting the results of experimental tests. Developed for a large introductory biology course, this case could also be used in an undergraduate microbiology course for pre-nursing majors to introduce the contemporary theory that many chronic medical conditions have an infectious origin. The case consists of a PowerPoint presentation (2.5MB) shown in class that is punctuated by multiple-choice questions students answer using personal response systems ("clickers"). It could be adapted for use without these technologies.

Whether Intelligent Design should be taught in a science classroom is a serious problem. This case study tackles the issue head-on by using intimate debate, a pedagogical structure in which small student groups are subdivided into opposing student pairs that take turns arguing each side of the issue. There is no audience for these concurrent mini-debates, and the session concludes with groups reaching consensus. This case study would be appropriate in general biology or advanced courses where the focus is on evolution.

This PBL case on Intelligent Design was written for freshman biology majors at a Christian liberal arts college. Students read about the claims and actions of proponents of Intelligent Design as they work for its inclusion in the high school science curriculum. In the process, students learn about the nature of science and the importance of evolution in the field of biology. More advanced students are given the task of critically evaluating one specific (and much cited) claim made by Intelligent Design supporters that the irreducible complexity of the bacterial flagellum suggests it cannot be the product of evolution.

In this case study, the evolution of human skin color is used as a means of exploring the process of evolution by natural selection. Through the progressive disclosure of data, students learn about are the factors that may have exerted pressure on the evolution of this trait. Students evaluate hypotheses, predict their outcomes, evaluate them in light of new information, and reformulate them to take unexplained data into consideration. The case has been used in a first-year introductory biology course for non-majors.

The overall purpose of this case study is to teach students to be skeptical of scientific claims, particularly those that are sensational and fall outside the boundaries of normal scientific explanation. Students read the case and then evaluate information to determine whether they believe there is enough scientific evidence to confirm the existence of extrasensory perception. The case was developed for use in an introductory science or psychology course, but would also be appropriate for courses in human biology in which the nervous system is explored.

In this interrupted case study, students explore the environmental consequences of Antarctic research as they design experiments to assess the impact of disposing untreated sewage from a research station into the ocean. Students review experimental methods to measure coliform bacteria, examine data, and decide what actions, if any, should be taken. The can be used in either a non-majors course in science literacy or a general microbiology class studying bacterial detection methods. For non-majors, the instructor would emphasize the mechanics of data collection and analysis and may touch on the environmental implications of finding fecal coliforms in Antarctic waters. For microbiology students, the instructor would highlight the bacteriology and pair the case with a lab.