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This case study introduces students to the "Red Queen Hypothesis." The hypothesis states that when two species compete for a limited resource or exist in a predator-prey relationship, in order for the antagonists to remain in relative population equilibrium, there must be ongoing and reciprocal adaptation on each side. If one species fails to adapt, it may quickly face extinction. Students are introduced to the Red Queen Hypothesis through an excerpt from Lewis Carroll's novel, Through the Looking Glass, in which Alice meets the Red Queen. They then review experiments from the research literature to evaluate the validity of the hypothesis in extant populations.  Students culminate their learning by contrasting their knowledge of the Red Queen Hypothesis to Darwinian evolutionary theory based on a passage from On the Origin of Species.  Students then craft a letter to Darwin helping to explain his "wedge" theory, a notion he originally developed but removed from later iterations of his book due to a lack of experimental evidence. Originally developed for advanced high school biology students, the case also may be used in a college-level introductory course on evolutionary biology.

This interrupted case study is designed to introduce beginning biology students to the process of science by exploring a question that is accessible to students with limited scientific background. The giraffe (Giraffa camelopardialis) is the tallest terrestrial mammal and has a disproportionally long neck. Historically, this trait has been hypothesized to be an adaptation for competition between the giraffe and other herbivore species. Guided by a PowerPoint presentation and (optional) worksheet, students will propose hypotheses to explain the giraffe's uniquely long neck and will examine the results of field experiments to test the prevalent historical hypothesis that the long neck allows the giraffe to exploit high food sources. They will find that the data do not support this initial hypothesis and will use other field observations to propose and examine an alternative hypothesis. Throughout the activity students will engage in the process of science; they will propose hypotheses, design experiments, make predictions, and draw conclusions from published field observations.

Because the gene-enzyme system forms a closed loop, it presents us with a classic chicken or egg conundrum: Which came first, genes or the protein enzymes they code for? While the details are still not fully worked out, discoveries over the past few decades have lead researchers to a surprising possible solution: What really came first? Genes that act as enzymes! The RNA World Hypothesis is the idea that before living cells, the genetic code, and the gene/protein cycle ever existed, chains of a chemical called RNA were forming naturally. Once formed, some of these chains were able to function as enzymes, and were even able to evolve by making copies of themselves with slight, accidental modifications.

Why is the North American population of monarch butterflies declining? In 1999, a study published in the journal Nature suggested that a variety of genetically modified corn was killing these iconic butterflies. While it was later shown that the conditions in this study did not mirror those in the field, the results garnered a lot of media attention and many people today still believe that monarchs are being killed by GMOs. This case familiarizes students with the plight of the monarchs, encourages them to think about how to test the hypothesis that a toxin is responsible for their decline, and takes a critical look at several studies that investigated the role of Bt corn in the life cycle of monarchs. This interrupted case takes 60-90 min to complete, requires little to no science background, and can be used to explore the ecology and wildlife management of monarchs; risk assessment, toxicity, and exposure; experimental design, the scientific method, hypothesis, and critical thinking; or the relationship between science, the media and the public.

In this article, we'll examine scientific ideas about the origin of life on Earth. The when of life's origins (3.53.53, point, 5 billion years ago or more) is well-supported by fossils and radiometric dating. But the how is much less understood. In comparison to the central dogma or the theory of evolution, hypotheses about life's origins are much more...hypothetical. No one is sure which hypothesis is correct - or if the correct hypothesis is still out there, waiting to be discovered.

The Aedes aegypti mosquito is the major vector for transmission of numerous viral diseases, including yellow fever, dengue, and now, Zika. Interestingly, different subspecies of A. aegypti are known to exist in close proximity but with considerable genetic divergence between them. One major difference between a "forest" form and a "domestic" form is a strong preference in the latter subspecies for human over non-human blood biting. This difference was explored with genetic and neurophysiological approaches by a research group at Rockefeller University and published in a 2014 paper in Nature. This flipped case study uses parts of the Nature paper to focus on elements of the scientific method as well as evolutionary questions raised by the difference in biting preference between the two subspecies. Students prepare for class by watching a video that provides background information about the published study that forms the basis for the case. In class students then work in groups to develop a hypothesis, predictions and proposed experiments to test the idea of different biting preferences.

In this video Paul Andersen explains how to run the student's t-test on a set of data. He starts by explaining conceptually how a t-value can be used to determine the statistical difference between two samples. He then shows you how to use a t-test to test the null hypothesis. He finally gives you a separate data set that can be used to practice running the test.

Paul Andersen shows you how to calculate the ch-squared value to test your null hypothesis. He explains the importance of the critical value and defines the degrees of freedom. He also leaves you with a problem related to the animal behavior lab. This analysis is required in the AP Biology classroom.

Could it be that Alzheimer's disease stems from the toxic remnants of the brain's attempt to fight off infection? Provocative new research by a team of investigators at Harvard leads to this startling hypothesis, which could explain the origins of plaque, the mysterious hard little balls that pockmark the brains of people with Alzheimer's.

This directed case study in PowerPoint format focusses on the London Underground Mosquito, Culex molestus, and its potential relationship to the common mosquito, Culex pipiens, in order to explore the topics of evolution, reproductive isolation, and speciation. As the story unfolds, the case mirrors the process of science. The students receive some initial data and observations collected by Byrne and Nichols in London. Based on these observations, the students then form a hypothesis and design an experiment. Finally, they receive more data collected by Becker et al. and draw conclusions.

Scientists were investigating a tantalizing but controversial hypothesis: that a man's experiences can alter his sperm, and that those changes in turn may alter his children.

The researchers, Eicke Latz at the University of Bonn and colleagues, followed up on the parents' hypothesis and found that in mice, cyclodextrin indeed blocked plaque formation, melted away plaques that had already formed in arteries, reduced atherosclerosis-associated inflammation, and revved up cholesterol metabolism-even in rodents fed cholesterol-rich diets. In petri dish-based tests, the researchers found that the drug seemed to have the same effects on human cells and plaques.

This case is an account of the events that led Drs. Robin Warren and Barry Marshall to the bacterial theory of ulcers. The two physicians refused to accept the standard explanations for what they had observed and instead developed an alternative hypothesis, saving countless patients from unnecessary pain and suffering. Along the way they transformed the way the medical community viewed peptic ulcer disease. The case shows the importance of curiosity, serendipity, and tenacity in scientific inquiry; how science is built upon the work of others; how assumptions can cloud people's views, leaving them closed to new ideas; and how scientific "truth" can and does change when faced with new data and new interpretations. It is appropriate for use in any course at the high school or undergraduate level that teaches students about the scientific method and/or the sociology, nature, and history of science.

This flipped case study is formatted as a PowerPoint presentation that uses group experimentation to encourage active learning in a large science classroom. There are options for using either wet bench experimentation or an online simulation, depending on the class goals. Students learn about plant transpiration and how it affects normal plant processes (photosynthesis). The basics of transpiration are covered in an animated video viewed outside of class. The experiment and/or simulation of transpiration can be conducted in or out of class. If the class is very large, the instructor may choose to assign the experiment/simulation for outside of class (post-video) and have the students bring their data to class, or the instructor may choose to just present the students with a data set from which they can work with their groups in class. At the end, students should be able to define transpiration, explain climate effects on transpiration rates, and how transpiration rates affect the overall physiology of the plant itself, through their own hypothesis design and experimentation.

Are you interested in using authentic Arctic and MOSAiC expedition data in your classroom? Look no further! Data Puzzles allow your students to analyze and interpret real scientific data and develop skills in hypothesis testing, graphing, and more.

The Underrepresentation Curriculum (URC) is a free, flexible curriculum for STEM instructors to teach about injustice and change the culture of STEM. Using tools such as data analysis, hypothesis creation, and investigation, students look critically at science through the lenses of equity and inclusion. By comparing the general population to similar data describing scientists, students can explore issues of social justice in STEM.

Science is working tirelessly night and day to disprove its own theories about how the universe works (or at least, that's what science thinks it's doing). Hank tells us a quick history of how we came to create and adopt the scientific method and then gives us a vision of the future of science (hint: it involves a lot more computers and a lot less pipetting).