This video segment adapted from NOVA shows how Galileo used his telescope to carefully observe and study sunspots.

Scientists don't always get it right. This video segment adapted from NOVA looks at Galileo's failed theory for the motion of the tides.

This video from NASA describes the GLAST satellite, which is equipped with a gamma-ray telescope, and shares some background about the kinds of extreme universal phenomena indicated by the presence of gamma rays.

This video segment from the Secret of Life School Video: "On the Brink: Portraits of Modern Science" explores the genetics of breast cancer.

The shared set of genes for body segments, possessed by all animals, are discussed in this video segment from Evolution: "Great Transformations."

In this video profile adapted from NOVA scienceNOW, learn about geneticist and rock musician Pardis Sabeti, whose innovative insights into natural selection demonstrated how beneficial mutations spread quickly through a population.

This ZOOMSci video segment teaches you how to germinate seeds in a plastic bag and helps you understand some of the factors that influence the germination process.

Learn how scientists regulate a nuclear reactor in this animation-enhanced essay from the FRONTLINE Web site.

This video segment, adapted from NOVA, chronicles the education of leading chemist Percy Julian. Although Julian began his elementary school years in the Deep South under Jim Crow laws, he became one of the few African Americans of his time to earn a Ph.D.

Featuring images of glacier formations, this interactive resource adapted from the National Park Service explains what glaciers are, where they are found, how they form, and how they move.

In this video adapted from the Encyclopedia of Physics Demonstrations, learn how a glass beaker vibrates at a specific frequency and how resonance can force it to shatter.

This video segment demonstrates carbon dioxide's role in the greenhouse effect and explains how increasing concentrations of C02 in the atmosphere may be contributing to global warming. Video includes an unusual demonstration of C02's heat-absorbing properties, using infrared film, a researcher's face, and a stream of C02 between them.

This video segment adapted from NOVA/FRONTLINE looks at the future of global warming as developing nations, including India and China, increase their need for energy.

Is the hydrogen car the answer to global warming? This video segment adapted from NOVA/FRONTLINE looks at the pros and cons of this developing technology.

This video segment adapted from NOVA/FRONTLINE examines the greenhouse effect, its role in keeping Earth habitable, and the industrial changes that have led to an increase in the planet's average temperature.

In this video segment adapted from Spanner Films, visit the Alaska Native village of Shishmaref, and learn how an entire town may be forced to relocate because of warmer temperatures, melting sea ice, and coastal erosion.

This video segment adapted from NOVA explores the effects of the Glen Canyon Dam on the beaches, wildlife, and vegetation of the Colorado River.

In this video segment adapted from NOVA, a fossil found among the Grand Canyon's rock layers reveals the existence of a shallow sea that once covered most of western North America.

This video segment adapted from NOVA features the youngest rock formations in the Grand Canyon, lava dams, and how they are subject to the eroding power of water.

In this lesson designed to enhance literacy skills, students learn how to read and interpret a distance–time graph.