This video segment describes how the Australopithecus afarensis skeleton known as Lucy could have been fossilized. Footage courtesy of NOVA: "In Search of Human Origins."

This video segment from NOVA: "The Mystery of Animal Pathfinders" explores honeybee communication and navigation.

Cocos Island, a remote volcanic summit in the middle of the Pacific Ocean, serves as a beacon for hungry predators, including thousands of hammerhead sharks that travel here each year in search of prey. This video segment from NOVA: "Island of Sharks" depicts some of the common predator-prey interactions that take place in the nutrient-rich waters surrounding the island.

In this video segment adapted from NOVA scienceNOW, scientists discuss their attempts to grow human body parts in a jar.

This video segment from Evolution: "Extinction!" shows the impact of invasive species on native ecosystems.

This ZOOM video segment shows how to create a self-contained environment and explores evaporation, condensation, and precipitation.

This interactive resource adapted from NASA describes the different temperature, precipitation, and vegetation patterns in seven biomes: coniferous forest, temperate deciduous forest, desert, grassland, rainforest, shrubland, and tundra.

There are almost as many types of bird beaks as there are types of food that birds like to eat. This collection of images shows a wide range of beaks and the types of foods handled by each.

In this video adapted from NASA, two members of a NASA research team working to produce carbon nanotubes share some background behind this new technology, show examples of how it will be useful, and explain the various tests being performed to ensure readiness for spaceflight.

In this video segment, adapted from NOVA, Dr. Judah Folkman uses the scientific method to discover how cancer cells induce the formation of new blood vessels, which in turn nourish those cancer cells.

Throughout the day, your nervous system monitors and makes endless adjustments to your body's basic systems -- all to keep you alive. This interactive feature illustrates the complexity of such a task.

This video segment, adapted from NOVA scienceNOW, presents basic concepts of physics behind booming sand dunes. See how surface tension affects potential and kinetic energy and how it all works together to create sound.

Find out how serious head concussions can be in this video segment adapted from NOVA scienceNOW.

In this interactive activity from the Building Big Web site, use your knowledge of bridge design to match the right bridge to the right location in a fictitious city.

In this video segment adapted from A Science Odyssey, learn about bubonic plague and how city officials in San Francisco tried to contain its spread in the early 1900s..

In this interactive activity from Shedd Aquarium, build a fish and then release it into the reef to search for food and evade predators. Try different combinations and observe how each kind of fish has unique adaptations that help it survive in its habitat.

In this video segment adapted from ZOOM, the cast shows how the 34 steps in their Rube Goldberg invention use everything from gravity to carbon dioxide gas in order to accomplish one simple task: pouring a glass of milk.

In this video segment from ZOOM, Jillian explains how her simple machine uses marbles, levers, flowing sand, and a spinning wheel to water a plant.

In this video segment from PEEP and the Big Wide World, children make a dam with dirt, sticks, and stones to try to stop the flow of water.

How do you build a tunnel 32 miles long -- under water? This video segment adapted from Building Big, follows the construction of the Channel Tunnel (nicknamed "Chunnel"), the engineering wonder that connects England to France.