This animation describes how skin color is generated by skin cells as protection against ultraviolet (UV) radiation.

In this case study, students use real data to propose hypotheses, make predictions, and justify claims with evidence, as an exploration of concepts presented in the short film The Biology of Skin Color.

This activity guides the analysis of a published scientific figure from a study that investigated genetic factors contributing to skin color differences, particularly within African populations.

A number of interactive questions are embedded within the short film The Biology of Skin Color, which explores the hypothesis that the variations in skin color in humans arose as adaptations to the intensity of ultraviolet radiation in different parts of the world.

In this activity, students explore how experimental work in zebrafish led to a better understanding of the role of the gene SLC24A5 in human skin color. The activity complements the film The Biology of Skin Color.

This activity explores an image of fossil footprints at Laetoli, which serves as a phenomenon for learning about fossil evidence and human evolution.

This video follows scientists working in Gorongosa National Park as they try to determine the genes responsible for tusk development in elephants.

In this Click & Learn, students explore mathematical models that describe how populations change over time and apply these models to the invasive lionfish population in the Bahamas. They also use data from other species to learn how density-dependent factors limit population size.

This animation shows the reactions of the citric acid cycle, which splits off carbon atoms and generates energy-rich reduced forms of cofactor molecules. It is the first of three animations about cellular respiration.

This animation shows how the proton gradient across the mitochondrial membrane powers the ATP synthase enzyme to make ATP. It is the third of three animations about cellular respiration.

This animation shows how the enzyme complexes of the electron transport chain harvest energy from cofactor molecules to pump protons across the mitochondrial membrane and establish a chemical gradient. It is the second of three animations about cellular respiration.

This interactive module explores the diversity of viruses based on structure, genome type, host range, transmission mechanism, replication cycles, and vaccine availability.

This film describes natural selection and adaptation in populations of rock pocket mice living in the American Southwest.

This three-part animation series explores the biology of the virus SARS-CoV-2, which has caused a global pandemic of the disease COVID-19.

This animation shows a single cycle of virus replication in a human cell.

This model shows the structure of dengue virus, which causes dengue fever.

This hands-on activity allows students to analyze DNA sequences of Ebola viruses. Students use these sequences to track the virus’s spread during the 2013–2016 Ebola outbreak in West Africa.