In this video segment from Cyberchase, the CyberSquad replaces a piece of track to get the Madre Bonita Express to the Mother's Day harvest.

In this media gallery, you will find a series of videos from The African Americans: Many Rivers to Cross that examines the major movements and turning points in African American history from 1968 to the present, including the Black Panthers and the Black Power movement, Afrocentricity in culture, the rise of the black middle class, the development of hip hop culture, the effects of the War on Drugs, and the election of Barack Obama. As you view the videos, consider the legacy of the civil rights movement, the tensions that emerged from the progress made, and how they reshaped the African American experience.

Noted Harvard scholar Henry Louis Gates, Jr. recounts the full trajectory of African-American history in his groundbreaking series The African Americans: Many Rivers to Cross. The series explores the evolution of the African-American people, as well as the multiplicity of cultural institutions, political strategies, and religious and social perspectives they developed — forging their own history, culture and society against unimaginable odds.

Using video clips from The African Americans: Many Rivers to Cross, this collection of lesson plans addresses a wide range of themes of the African-American experience from 1500 to the present.

In this video from Nature, geological detectives use ancient diamonds to learn more about Earth's inner layers.

See the many birds that spend their summer in the Arctic in this video segment from Nature.

The CyberSquad tries to figure out a table arrangement for 20 workers in this video from Cyberchase.

In this video segment from Cyberchase, Matt tries for a second time to arrange tables and chairs to accommodate 20 workers.

Matt's third table arrangement helps fit all 20 workers at five tables in this video segment from Cyberchase.

In this video segment from TV411, figure skaters compute their average daily practice time.

This Nature video segment focuses on the four foods most important to the grizzly bears' survival, and it describes the threats to the supply of each of them.

In this video segment from Nature, learn about the problems bears are creating on ranch land surrounding Yellowstone National Park.

This Nature video segment explores how the relationship between humans and grizzly bears has changed over the course of American History, and it describes the closing of the Yellowstone National Park garbage dumps in the 1970s.

Learn about the precautions humans must take in the face of a growing grizzly bear population in this video from Nature.

Bianca visits a bike shop and learns how bicycle gears work in this Cyberchase video segment.

This Cyberchase video segment features Bianca, who must figure out the fastest route to a movie premiere.

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

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

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.

This video segment from The Human Spark observes the brains responses to a series of cognitive tests.

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_