In this video segment adapted from NOVA, dramatic footage of avalanches and animations of ice crystals illustrate how a layer of weakly-bonded snow can contribute to a devastating avalanche.

In this video segment adapted from NOVA, scientists use computer simulations to explore the question of how supercell thunderstorms produce tornadoes.

This video segment adapted from FETCH! shows contestants experimenting with different materials to see which is the best insulator and thus best able to keep the lemonade at their stand cool for customers.

Aaron and Justin investigate which sunscreen best keeps out harmful ultraviolet rays from the Sun, in this video from DragonflyTV.

This illustrated essay from A Science Odyssey Web site explains the science behind radio waves, including the role of electrons and electromagnetic fields.

In this video segment adapted from Shedding Light on Science, observe demonstrations of the fundamental idea that light travels in straight lines.

This video segment adapted from KET's Where the River Bends demonstrates how climate change and glacier movement during the Ice Ages destroyed the old Teays River and created the Ohio River, Kentucky's northern border.

In this fast-paced NASA Brain BitesŒ_íěÖ video, an astronaut demonstrates the impact of microgravity on the use of tools in space.

In this video segment adapted from NOVA, follow novice runners as they train for a marathon, and discover how quickly the body responds to regular aerobic exercise.

In this video segment adapted from NOVA, explore the theory that small bits of gas and dust combined to form protoplanets billions of years ago, which in turn collided to create the four rocky planets of the inner solar system.

Learn how the Hawaiian Islands were formed by a geothermal hotspot and resulting volcanic activity in this video segment from Nature.

In Blazing a Genetic Trail, by the Howard Hughes Medical Institute, follow this three-step approach to treating genetic diseases.

This video segment adapted from the Space Telescope Science Institute shows what the Hubble telescope found when it stared at a single, nearly empty spot in the sky for 10 days in 1995. The unexpected result was a picture of a multitude of galaxies stretching into the distance.

Students learn how the human body self-regulates to maintain a stable internal environment despite changes in the external environment.

In this video segment adapted from NOVA: Judgment Day: Intelligent Design on Trial, learn how modern genetics and molecular biology offer compelling support for evolution. The video features an interview with biologist Ken Miller.

Students investigate hominid evolution. They learn the difference between a relative and an ancestor, study the emergence of bipedalism, and chart patterns of hominid migration.

This video segment from NOVA: "Cracking the Code of Life" looks at the meaning and significance of the effort to decode the human genome.

This video segment from The Human Spark features a discussion about how human thought differs from that of chimpanzees.

Learn about the wildebeest and locusts on the move in this video segment from Nature.

In this video segment adapted from the National Film Board of Canada, learn how the Inuit people have used their traditional knowledge to understand and adapt to changes in their Arctic environment, particularly when hunting and navigating the landscape.