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En Garde! Animal Structures and What They Mean
In most animals, the drive to breed and produce offspring is strong. However, most males live their whole lives without having the chance to breed. The events leading up to mating can be very dangerous and also very costly to an individual. Some males ...

A Deadly Passion
This "clicker case" teaches students about the distinction between proximate and ultimate causes of behavior using the fascinating courtship and mating rituals of the Australian redback spider. The case is presented in class via a PowerPoint presentati...

A Decision to Branch Out
In this flipped case study, students use the scientific method to investigate how changes in a few genes have shaped the evolution of maize plant architecture during domestication. To prepare for the case, students first watch a video developed by HHMI...

A Strange Fish Indeed
Through a series of fictionalized diary entries, this case recounts the 1939 discovery by Marjorie Courtenay-Latimer (and identification by J.L.B. Smith) of a living coelacanth, a fish believed to be extinct for over 70 million years. Developed for...

A Tale of Three Lice
This “clicker case” explores the questions of when hominins lost their body hair and began wearing clothing by examining the surprising phylogeny of human head, body, and pubic lice. Students are led through the scientific process as they a...

A Whale of a Tale?
For years whale evolution was characterized by speculation and limited evidence. Evolution critics even focused on whales as a means to criticize evolutionary theory. Now whale evolution represents one of the best examples of "macroevolution." This "cl...

Aliens on Earth?
The discovery of a bacterium capable of substituting arsenic for phosphorus in its DNA was announced with much fanfare in 2010. It was immediately and very publicly critiqued by researchers posting their analyses of the paper on their blogs. The author...

An Antipodal Mystery
The discovery of the platypus had the scientific world in an uproar and kept it tantalized for decades. Here was the strangest animal ever seen. How was one to classify it? It had fur. So, was it a mammal? But then what to make of its duck-like bill? A...

An Infectious Cure
This four-part interrupted case on phage therapy was developed for a freshmen non-majors course in molecular biology. The case begins with a story inspired by real events where Europeans imposed a treatment for cholera on the unwilling population of an...

And Now What, Ms. Ranger?
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 rea...

Antibiotic Resistance
Resistance to antibiotics arose very shortly after these "wonder drugs" were first introduced.  This case study examines resistance to the most commonly used antibiotics, penicillin and its derivatives.  In particular, it examines a recent st...

As the Worm Turns
At what point in evolutionary development does a group of individuals become two distinct species? This case addresses that fundamental question by asking students to decide whether apple maggot flies are distinct as a species from hawthorn maggot flie...

Blood Suckers! A Case Study on Evolution and Speciation
This directed case study in PowerPoint format focuses 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 ...

Breeding Belyaev's Pets
This clicker case addresses several important concepts related to evolution. First, it explores artificial selection and selective breeding. Charles Darwin used artificial selection as an example to support his Theory of Evolution by Natural Selection....

BSL-4: Authorized Personnel Only
This case study is based on the 2014 Ebola epidemic that spread to multiple highly populated countries in West Africa, making it the largest and most devastating outbreak in the history of the virus. The storyline, inspired by a compilation of factual ...

Chimpanzee Droppings Lead Scientists to Evolutionary Discovery
This interrupted case study focuses on the research of Dr. Beatrice Hahn, who investigates DNA sequences in chimpanzee droppings in order to explore the origins of the human immunodeficiency virus (HIV). Students first consider the types of data that c...

Crazy About Cryptids! An Ecological Hunt for Nessie and Other Legendary Creatures
Who wouldn't want to go in search of a creature like Bigfoot, Yeti, or the Loch Ness Monster?  Using the science of ecology, students do exactly that in this case study that encompasses a variety of case study teaching formats.  Working in gr...

Cross-Dressing Salmon
This "clicker case" about female mimicry in spawning salmon was developed for an introductory-level, non-majors biology course to help address one of the most common misconceptions that students have about natural selection, namely, that only the "stro...

Darwin's Finches and Natural Selection
In this "clicker case," students learn about natural selection through the research of Peter and Rosemary Grant and colleagues on the finches of the Galapagos Islands. Students are presented with data in the form of graphs and asked to determine what i...

Ecology of Individuals: Using Game Theory to Understand Animal Behavior
This case study is based on the game theory developed by John Maynard Smith where two behavioral strategies ("Hawks" and "Doves") compete over a contested resource. During this 50- to 75-minute case, students experience "hands-on"' the change in freque...

Equal Time for Intelligent Design?
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 pair...

Evolution and Plasticity in Guppies
This case study focuses on the relationship between evolution and plasticity using a hands-on, inquiry-based approach. Students view examples from the literature that illustrate the difference between nature and nurture, or the relative contributions o...

Exaggerated Traits and Breeding Success in Widowbirds
Sexual selection has led to the evolution of interesting traits and behaviors in many animal species. In widowbirds, males undergo a dramatic change in plumage coloration and produce exceptionally long tail feathers during the breeding season. This cha...

Genetics and a Transcontinental Romance
Annika is a PhD student from Sweden who spends two years in the Solomon Islands to complete her fieldwork. During her stay in the South Pacific she experiences a few surprises related to the hair color not only of the locals, but also of her own baby g...

Got Blood?
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 wit...

How Many More Thymes? A Case of Phytochemical Defense
This clicker case addresses several concepts related to the evolutionary ecology of herbivore defenses. A survey of several different studies that investigated chemical defenses in Thymus vulgaris (thyme) gives students the opportunity to deve...

I Scream for Ice Cream
Lactose intolerance, caused by a lack of persistent lactase enzyme expression, is a trait commonly observed in adult humans, with varying geographic prevalence depending on dietary habits in different cultures. This case study follows a diverse group o...

I'm Looking Over a White-Striped Clover
This case is an exploration of the process of natural selection using white clover (Trifolium repens) as an example. In general, two forms of white clover can be found around the world in various habitats. One type is able to produce cyanide i...

It’s a Crocodile! No, a Fish! No, a Dolphin!
It is not uncommon to hear creationists argue that evolution is not science because no one saw it happen, or for students to wonder how we can know anything about the physiology or behavior of organisms that went extinct hundreds of millions of years a...

Joel E. Greengiant Learns About Peas
This case study follows purveyors of peas, Joel E. and Jolene Greengiant, as they learn about the origin, biochemistry, genetics and eventual artificial selection of sweet (wrinkled) peas, all in the context of evolutionary biology. This integrative ap...

Just a Spider Bite?
This case relates the story of two fictional college students, Kristen and Brent, who discover that they are infected with Staphylococcus aureus. Brent recovers after using an antibiotic, but Kristen does not. It is later confirmed through tes...

King Tut's Family Secrets
This "clicker case" is based on several articles published in 2010 that determined the genealogy of the ancient Egyptian pharaoh Tutankhamun based on microsatellite DNA analysis. The case begins with a description of the seven royal mummies found in Va...

Little Mito
This case presents a fanciful story about the origin of the eukaryotic cell, a major milestone in the evolution of life. The characters of the story are Mito, Chlora, Flag, ER, Nuc, Golgi, Ves, and Ly, all members of an extended cellular family. Writte...

Man's Best Friend?
In this case, students learn how archaeology operates as an historical science by collecting and analyzing material evidence to make claims about the past. Assuming the role of zooarchaeologists, they evaluate a hypothetical case in which “Dr. Ja...

Mathematics in Conservation
This interrupted case study teaches probability theory and transmission genetics through their application to the conservation of the endangered Florida panther. An endangered population is unlikely to survive simply due to its small population size. B...

MDR Tuberculosis
In this case study on multi-drug resistant (MDR) tuberculosis, students consider ways in which to preserve health as a human right without subjecting already marginalized communities susceptible to the disease to further discrimination. Students learn ...

Mom Always Liked You Best
This interrupted case study is based on a journal article on the parenting behavior of American coots. Working through the case, students develop hypotheses and design experiments to test their hypotheses as they are given pieces of the case in an inte...

My Brother's Keeper
In this interrupted case study, students work in teams to interpret behavioral data with respect to evolutionary biology.  Specifically, the case examines the behavior of alarm calling in a certain type of squirrel, Belding's ground squirrel, whic...

No Bats in the Belfry
This interrupted case study investigates the geographic origin of white-nose syndrome (WNS) in little brown bats (Myotis lucifugus). WNS is a devastating fungal disease caused by the fungus, Pseudogymnoascus destructans (formerly know...

Not Necessarily on Purpose
In this “clicker case,” students learn about evolution, speciation, and natural selection as well as interpret phylogenies as they apply to the Canidae family. The case is based on the idea that the domestication of the dog was not likely a...

Of Mammoths and Men
The discovery of a mammoth frozen in the Siberian tundra is the backdrop for this case study, which explores theories for the extinction of the great Ice Age mammals and Homo neanderthalensis. Students research evidence for and against the dif...

Patient Zero
Emerging diseases and potential pandemics make the news nearly every year. Students (and everyone else) may wonder where new infectious diseases come from, how scientists assess the risk of a pandemic, and how we might go about preventing one. This cas...

Poor Devils
Cancer is usually thought to be a disease that affects individuals. But could cancer evolve to become infectious? This case follows the research on a form of transmissible cancer that is decimating the Tasmanian devil, the world’s largest carnivo...

Reproductive Isolation in Columbines
This clicker case uses plant-pollinator interactions in columbines as a biological scenario to teach students about evolution, reproductive isolation, and angiosperm reproduction. The case is based on an approach to evolution education called tree-thin...

Selection and the Blond Beach Mouse
This "clicker" case study explores ultimate and proximate explanations for cryptic coloration in animals through the work of Dr. Hopi Hoekstra of Harvard University, who studies Gulf and Atlantic Coast beach populations of oldfield deer mice that have ...

Seven Skeletons and a Mystery
This problem-based learning case uses Archaeopteryx, the most famous fossil in the world, to show the vital role that fossils play in understanding evolutionary history and to explore the different theories for the origin of flight and the deb...

Shooting the Poop
This group-based case study is based on research by Dr. Martha Weiss using silver-spotted skipper caterpillars (Epargyreus clarus (Lepidoptera)). These insects perform the unusual behavior of flinging their frass (excrement) great distances aw...

Should Dinosaurs Be Cloned from Ancient DNA?
Michael Crichton's Jurassic Park, as a novel and then a blockbuster movie, reawakened the public's fascination with dinosaurs. Although dinosaurs have always been popular, Spielberg's sophisticated cinema computer graphics thrilled human imagi...

Super Bug
Sam, a pre-med college student, routinely gets dialysis and develops a urinary tract infection. The infection is from a bacterium that the news media is calling a "superbug" from India. Sam does some internet searches to find out more information about...

The Case of Desiree's Baby
This case is based on Kate Chopin’s short story “Desiree’s Baby,” a tragic tale of race and gender in antebellum Louisiana first published in 1893. Students read the story and then answer a series of questions about the genetics...

The Case of the Sexually Arrested Orangutans
This case examines the hormonal control of the development and maturation to adulthood and the role of stress hormones in that developmental process. The case was adapted from results summarized in Maggioncalda and Sapolsky’s (2002) article in

The Coelacanth: An Odd Fish
This "clicker case" is a redesign of a case, also in our collection, by Robert H. Grant titled "A Strange Fish Indeed: The 'Discovery' of a Living Fossil." The case follows the story of Marjorie Courtenay-Latimer and her discovery of the coelacanth, a ...

The Dangers of Deicing
Loss of species richness is often due to anthropogenic activity. The global decline of amphibians is one such example. This case study examines the impact of road deicing agents on amphibians living near bridges and roads treated heavily with salt duri...

The Dating Game
In this role-playing case study, students attempt to determine the identity of a variety of human fossils based on characteristics described during a “quiz show.”  The case was designed to be used in a general biology class for freshma...

The Death of Baby Pierre
This directed case study on a genetic disorder was developed for an exam on genetics for a general biology course.  The case is based on an article by scientist and author Jared Diamond titled “Founding Fathers and Mothers” that appear...

The Evolution of Color Vision in Monkeys
This case study examines the evolution color vision in Old World and New World monkeys from multiple biological perspectives. This integrative approach employs both problem-based learning techniques and directed questions as students move through a ser...

The Evolution of Creationism
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 cu...

The Evolution of Human Skin Color
While the concept of evolution by natural selection is very simple, it is often misunderstood by students. This is partly due to preconceptions they have as well as a lack of understanding or emphasis on the idea that reproductive success (and not surv...

The Galapagos
Using problem-based learning and role-playing, students analyze the geological origins of the Galapagos Islands, their colonization, species formation, and threats to their biodiversity in this story of a graduate student caught between local fisherme...

The Itsy-Bitsy Spider: An Analysis of Spider Locomotion
The evolution of physiological characteristics can be strongly influenced by physics. Animals whose physiology allows them to better escape predators will live longer, on average, and be more likely to pass on the genes that led to these favorable trai...

The Missing Link
The setting for this case study is a paleontological dig in East Africa, where “Sam,” an American undergraduate student, has unearthed part of what appears to be an ancestral human skull. Students read the case story and then, in the lab, t...

The Modern Caveman’s Dilemma
During the Paleolithic era, human life expectancy was only 33 years—roughly half of what it is today. We owe our more extended lives in part to better hygiene, medicines, and more plentiful foods. Yet some people aspire to return to that earlier ...

The Molecular Origin of Life: Replication or Metabolism-First? Advanced Version
This case explores both the evidence and inconsistencies in the two major hypotheses for the origins of life on Earth: Replication-First or Metabolism-First. The case has two versions published on this website - one is written at the introductory level...

The Molecular Origin of Life: Replication or Metabolism-First? Introductory Version
This case explores both the evidence and inconsistencies in the two major hypotheses for the origins of life on Earth: Replication-First or Metabolism-First. The case has two versions published on this website - one is written at the introductory level...

The Spark of Life
In biology classes, students are typically taught that spontaneous generation does not take place. And yet, at the origin of life, life had to arise without parents from abiotic processes. What were those processes that gave rise to the first life?&nbs...

The Story of Dinosaur Evolution
In this case study, students write their own “evolution stories” based on information taken from a review article by Paul Sereno on the evolution of dinosaurs published in Science magazine. In the process, they learn to distinguish...

The Waiting Game
In this interrupted case study, students examine the cooperative courtship behavior of long-tailed manakins. Males of the long-tailed form leks, areas in which males display for females in groups. Leks in this species consist of two to 11 males, with t...

Threats to Biodiversity
In this case study, students learn about introduced species and how they pose a threat to biodiversity by analyzing the impact of introduced species on the native bird populations of the Hawaiian Islands. Developed for an introductory biology course, t...

Trouble in Paradise
In this case study, students apply principles of evolution they have learned in class to create their own story explaining the evolutionary history of a previously unknown species of rodent discovered on an island in the West Indies. The case study is...

Unintended Consequences of Plant Domestication on Plant-Insect Interactions
This case study investigates how plant domestication sometimes produces unintended consequences for plant-insect interactions. The narrative follows a boy in middle school, Podrick, who goes on a class field trip and notices that there are no caterpill...

What is a Species?
This "clicker case" is modified from Martin Kelly's case study "As the Worm Turns: Speciation and the Apple Maggot Fly," also in our collection. Classic cases of incipient speciation such as the apple maggot fly and the hawthorn maggot fly are an excel...

When Wilma Met Fred
This "clicker case" follows a professor and his students in a study abroad course in Tanzania who are searching for human fossils in an effort to better understand where humans come from. The case story, presented as a PowerPoint presentation, is compl...

Which Came First, the Mutation or the Antibiotic?
This case study presents the story of Phil, an undergraduate majoring in biology, whose Russian cousin Dimitri has contracted tuberculosis (TB) from inmates at the prison where he works.  Phil learns that his cousin's failure to complete his antib...

Why Did the Snake Cross the Road?
Although Hardy-Weinberg equilibrium is a fundamental part of introductory biology classes, students often have difficulty understanding its implications. This interrupted case study places students in the role of small teams who are conducting prelimin...

Why Sex is Good
This interrupted case is based on a 2005 article in Nature written by three scientists from the Imperial College London that deals with the issue of sexual vs. asexual reproduction and their relative merits—a question that has bedeviled ...