In this video from DragonflyTV, follow the investigation of Isaac and Anjali as they record, measure, and analyze data about how the Sun's position in the sky affects a solar-powered car's speed.

What is a solar eclipse and why are they only visible in some parts of the world? In this video segment adapted from NASA, astronomer Susan Stolovy uses animations to provide an answer to these questions.

In this video segment adapted from ZOOM, cast members assemble a solar still and make fresh water from saltwater, demonstrating two steps of the water cycle, evaporation and condensation.

In this video segment from Religion & Ethics Newsweekly, view the reactions of citizens from Lewiston, Maine as Somali immigrants settle in their community.

This interactive quiz from the NOVA Web site features an array of interesting facts about the nature of sound underwater.

This video segment, adapted from ZOOM, explores how sound waves travel differently through solids than through air, in this case, a metal clothes hanger.

In this video segment from Cyberchase, Hacker and the CyberSquad race to reach the Good Vibration on staircases that grow at different rates and have steps of varying sizes.

This video segment adapted from Shedding Light on Science uses historical illustrations and everyday examples to show that light has a speed and does not travel instantaneously.

In this video adapted from the University of Alaska, Anchorage, Alaska Native people of Chevak teach visitors about the beauty of Cup'ik culture and the spirit of the earth, sea, and animals.

In this video profile produced for Teachers' Domain, meet conservationist Steve MacLean, an Inupiaq from Barrow, Alaska, who works to preserve the health of the Bering Sea ecosystem.

Studying life on the seafloor beneath Antarctica's thick ice is a major challenge for ecologists. Learn about a new device that can reach those icy depths in this video segment adapted from WomenInAntarctica.com.

This video segment from FRONTLINE/NOVA: "Harvest of Fear" explores genetic modification of salmon and possible consequences.

The peacock provides a classic example of sexual selection, the force behind nature's extravagances. From Evolution: "Why Sex?"

Bonnie Chen builds on students' prior knowledge of mutations to lead her class through a simulation of wading birds feeding.

Marilyn Havlik leads students through a simulation of the Hardy-Weinberg Principle to develop their understanding of population genetics.

In this video adapted from KUAC-TV and the Geophysical Institute at the University of Alaska, Fairbanks, learn how tectonic plate movement is responsible for building mountains, such as the Wrangell and St. Elias Mountains.

This interactive activity produced for Teachers' Domain shows the relationship between tectonic boundaries and the locations of earthquake events and volcanoes around the world.

In this transcript of an interview filmed for Evolution: "Great Transformations," Ted Daeschler and Neil Shubin describe the discovery and significance of some of their key fossil finds.

Why do teenagers act the way they do? This video segment from FRONTLINE: Inside the Teenage Brain explores the work scientists are doing to explain some of the mysteries of teenage behavior.

Watch the ZOOM cast discover which insulator -- newspaper or aluminum foil -- is better at keeping an ice cube frozen longer.