In this video segment from ZOOM, Hillary, from Randolph, MA, takes us on a tour of the columns in her neighborhood.

The CyberSquad proves that the area of Hacker's land is equal to the area of Judge Trudy's land in this video segment from Cyberchase.

In this video from Cyberchase, Harry must score a total of 50 points in various events to qualify for the Northern Hemisphere games in New Orleans.

In this text excerpted from chapter 3, Struggle for Existence, of Charles Darwin's On the Origin of Species, Darwin draws on firsthand and historical information for his observations about evolution.

The levels of contaminants found in particular animals vary widely depending on where they fit into the Arctic food chain, as described in this video segment adapted from LOKE Films and the Arctic Monitoring and Assessment Programme.

In this video segment adapted from LOKE Films and the Arctic Monitoring and Assessment Programme, learn how human populations in the Arctic are affected by industrial contaminants in the food chain.

This video segment adapted from the Atmospheric Radiation Program explains the differences in the formation of tropical convective cloud systems over islands and over the ocean.

In this Cyberchase video segment, Matt uses subtraction to help Digit figure out how much time he has left in a cooking contest with Hacker.

In this video segment adapted from ZOOM, two solar cookers are tested against a control to see which can cook a "s'more" faster.

In this video segment, ZOOM guest Cassie takes us on a tour of the coral reef near her home in Key Largo, Florida, and points out some of its unique features.

This interactive activity from ChemThink takes a closer look at a covalent bond--how it is formed and how the sharing of two electrons can keep atoms together.

In this video segment from Cyberchase, the CyberSquad must get into a vault before Hacker, Buzz and Delete by cracking a code of shapes and numbers.

In this video segment from Nature, learn the geological process by which the next Hawaiian island will be formed.

In this Cyberchase video segment, Shari Spotter gets help from the CyberSquad in doubling a recipe for crumpets.

In this interactive activity from the Building Big Web site, investigate dams in distress and decide if they should be repaired, removed, or left alone.

This video segment from Evolution: "Darwin's Dangerous Idea," together with interviews with Daniel Dennett and James Moore, depicts Darwin struggling with publicizing his revolutionary theory.

In this video segment adapted from NOVA, scientists search for carbonized remains of plants preserved in lava flows to find out how long it has taken rain forests on Hawaii to regenerate after a volcanic eruption.

This video segment, adapted from Decision in the Streets by civil rights filmmaker Harvey Richards, portrays the interracial protests that took place in San Francisco in 1963-64.

Without the work of decomposers, living organisms would eventually use up all the raw materials in the environment, and dead organisms and wastes would pile up. This video segment from Interactive NOVA: "Earth" describes the role of decomposers as the earth's great recyclers.

In this video segment adapted from ZOOM, cast members use a hair dryer to balance a ball in a stream of air, seemingly defying gravity.