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All introductory biology textbooks, and many sophomore-level genetics textbooks as well, describe several classic experiments in molecular biology. This interrupted case study takes students through two of these classic experiments, namely, those by Griffith and Avery, McCarty and MacLeod that showed DNA to be the genetic material in Streptococcus pneumoniae, and the experiment by Meselson and Stahl that demonstrated DNA replication to be semiconservative. Engaging students with the experiments in a more exploratory manner can reinforce the nature of scientific discovery and the logic behind these findings. The case, which has been formatted as two separate exercises that can be used independently, was developed for use in introductory biology classes for biology majors. The material is accessible enough to also be useful for non-majors college biology or high school AP biology students.

Many biology courses are designed to develop student understanding and application of the scientific method, but few seriously examine the various ethical questions associated with scientific research. This interdisciplinary case study presents three experiments and asks not only if they are scientifically valid but whether they were ethically performed.  The experiments examine the psychology of love, a cause of breast cancer, and how the immune system functions in the presence of cancer. Based on their opinions of the validity and ethics of each experiment, students are asked to conclude which of the experiments were actually conducted by scientists and which are fictional. Students should already be familiar with the scientific method, but information on the Georgetown Mantra and Nuremberg Code.is included. The case could be modified for use in non-majors and majors classes.  The format of the case challenges students of any background to use information from both science and ethics to see how the differing approaches of scientist and ethicist can complement and strengthen each other.

The Miller-Urey experiment was the first attempt to scientifically explore ideas about the origin of life. Stanley Miller simulated conditions thought be common on the ancient Earth. The purpose was to test the idea that the complex molecules of life (in this case, amino acids) could have arisen on our young planet through simple, natural chemical reactions. The experiment was a success in that amino acids, the building blocks of life, were produced during the simulation. The finding was so significant that it kick started an entirely new field of study: Prebiotic Chemistry. Scientists now have reason to believe that the gases used in the Miller-Urey simulation were not actually the same as those of the ancient atmosphere. Because of this, many experiments have since been done, testing a wide variety of atmospheres and different environmental conditions. The results are overwhelming: the molecules of life can form under a wide variety of ancient Earth-like conditions. Many questions about the origin of life remain to be answered but these findings give strong support to the idea that the first living cells on Earth may have emerged from natural chemical reactions.

This set of mini cases on the ecology of eastern cottontail rabbits is designed to give students practical experience using statistics in a scientific context. Given a dataset and experimental design, groups of students are asked to play the part of a wildlife management researcher to determine the results for each study. Students practice the scientific process and gain experience making hypotheses and predictions, choosing an appropriate statistical test, interpreting and displaying results, and presenting data to others. Students choose between four basic, commonly used, statistical tests (t-test, one-way ANOVA, linear regression, and Chi-square test), and justify their choices. This activity was developed for undergraduate level students and is applicable to biology courses, particularly those dealing with ecology or management. The case is designed for student groups, but could be modified into clicker questions or individual assignments.

The short film opens with two questions: "So what determines how many species live in a given place? Or how many individuals of the species can live somewhere?" The research that provided answers to these questions was set in motion by key experiments by ecologists Robert Paine and James Estes. Robert Paine's starfish exclusion experiments on the coast of Washington state showed that removing starfish from this marine ecosystem has a big impact on the population sizes of other species, establishing the starfish as a keystone species. James Estes and colleague John Palmisano discovered that the kelp forest ecosystems of the North Pacific are regulated by the presence or absence of sea otters, which feed on sea urchins that consume kelp. These direct and indirect effects of sea otters on other species describe a trophic cascade. These early studies were the inspiration for hundreds of investigations on other keystone species and trophic cascades, as well as ongoing studies into the regulation of population sizes and species numbers.

Adverse life experiences, particularly those in childhood, contribute to disease morbidity and mortality [1, 2, 3, 4, 5, 6, 7]. There is considerable interest in understanding the mechanisms through which they do so, as it remains unclear how illness becomes apparent decades after the presumed initiating event. Long-standing hypotheses include chronic activation of the hypothalamic-pituitary-adrenal axis [8, 9, 10] and alterations of neuroimmune function [11]. Molecular signatures of stressful life experiences and their relation to disease are therefore of special interest to clarify the causal relationship between signature, disease, and stress.

Everyone experiences pain -- but why do some people react to the same painful stimulus in different ways? And what exactly is pain, anyway? Karen D. Davis walks you through your brain on pain, illuminating why the "pain experience" differs from person to person.

While scientists study how nature works, engineers create new things, such as products, websites, environments, and experiences. Because engineers and scientists have different objectives, they follow different processes in their work. Scientists perform experiments using the scientific method; whereas, engineers follow the creativity-based engineering design process.

The question of cell renewal is one that all of us have intuitive daily experience with. We all notice that our hair falls out regularly, yet we don't get bald (at least not until males reach a certain age!).  Similarly, we have all had the experience of cutting ourselves only to see how new cells replaced their damaged predecessors. And we donate blood or give blood samples without gradually draining our circulatory system. All of these examples point to a replacement rate of cells, that is characteristic of different tissues and in different conditions, but which makes it abundantly clear that for many cell types renewal is a part of their story.

This activity can be used in conjunction with the short film The Double Helix. It introduces students to the classic experiment by Matthew Meselson and Franklin Stahl, which revealed that DNA replication follows the semiconservative model.

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. Belyaev's Fox-Farm experiment is used as an example of a study that used selective breeding as the primary experimental procedure to investigate changes in a lineage. Second, it addresses an interesting observation made by Charles Darwin in The Origin of Species in which he noted how domesticated species also show interesting traits such as drooping ears which seem to be common in domesticated species. The "Farm-Fox Experiment" not only demonstrates how a research team can thoroughly investigate an intriguing question, but also serves as a classic example of elegant experimental design. Designed for use in a large introductory-level biology class, this case study would also be appropriate for smaller classes as well as for upper-level evolution courses.

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?  This case study uses an interrupted format to guide students through the Miller-Urey experiment of 1953, which showed that organic molecules could be produced from abiotic precursors and conditions thought to be prevalent on the early Earth. The case also addresses the more speculative implications about where these reactions may have taken place to create the organic building blocks of life on this planet. The first three parts of the case, which explore the Miller-Urey experiment, are ideal for introductory biology courses and take about 45-50 minutes to complete. The remaining sections, which explore whether such chemical reactions took place in outer space, were used in a non-major astrobiology course and require a further hour to complete.

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.

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.

Teaching K-12 Science and Engineering During a Crisis aims to describe what high quality science and engineering education can look like in a time of great uncertainty and to support practitioners as they work toward their goals. This book includes guidance for science and engineering practitioners - with an emphasis on the needs of district science supervisors, curriculum leads, and instructional coaches. Teaching K-12 Science and Engineering During a Crisis will help K-12 science and engineering teachers adapt learning experiences as needed to support students and their families dealing with ongoing changes to instructional and home environments and at the same time provide high quality in those experiences.

Animated primer of 75 key historical experiments in modern genetics

After apologizing for an American science experiment in which Guatemalan prisoners and mentally ill patients were deliberately infected with STDs more than 60 years ago, U.S. officials called on the Institute of Medicine to launch a full investigation. NBC Chief Science Correspondent Robert Bazell reports.

Hank tells us the stories of three experiments in biology that, with creativity and luck, changed science & the world with it in their work to solve the mysteries of the universe.

Your ancestors' lousy childhoods or excellent adventures might change your personality, bequeathing anxiety or resilience by altering the epigenetic expressions of genes in the brain.

This case study centers on symbiotic relationships between insects and bacteria using Drosophila melanogaster, the common fruit fly, and the recently discovered bacterial species Sodalis praecaptivus. Until recently, the only known Sodalis species of bacteria were symbiotically associated with several different species of insects. However, free-living non-symbiont Sodalis species are being tested in several different insect species to determine if they can transition into symbiotic relationships. A pre-class assignment (see Supplemental Materials) directs students to read an open access research journal article providing a comprehensive review of S. praecaptivus and describing an experimental weevil model that parallels that of the fruit fly. A PowerPoint presentation shown in class (see Supplemental Materials) provides further background before students work in small groups to complete the case study focusing on results from D. melanogaster and S. praecaptivus model experiments.  Although developed for a genetics course, this interrupted case is appropriate for an upper-level biology course. It can be completed within a 75-minute class meeting, or adapted for shorter time periods.