This video segment from Cyberchase introduces the idea of inverse operations as Bianca imagines herself as a spy.

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 Nature video, learn about the extraordinary impact that birds have on the agriculture of a small Indian community.

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.

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 video excerpt from Dinosaur Train, Buddy and Tiny name species of dinosaurs from Apatosaurus to Zigongosaurus when they sing the "Dinosaurs A to Z" song with the help of Mr. Conductor. ***Access to Teacher's Domain content now requires free login to PBS Learning Media.

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.

As an assistant attorney general in the Civil Rights Division of the Department of Justice, Burke Marshall played a key role in the federal government's efforts to desegregate the South. Representing the presidential administrations of John F. Kennedy and Lyndon B. Johnson, Marshall mediated conflicts between civil rights protesters and southern white officials. In this interview, Marshall recalls the 1961 Freedom Rides and the 1962 desegregation of the University of Mississippi.

In this video segment from Between the Lions, Leon Redbone sings a fun alphabet song. In alphabetical order, each letter takes the stage along with a Between the Lions character or image that begins with that letter. Showing the letters and things they stand for helps build alphabet knowledge. ***Access to Teacher's Domain content now requires free login to PBS Learning Media.

In this Cyberchase video segment, the CyberSquad must estimate the measurements of Spout the Whale in order to find a cage that will fit him.Ű_í_