In this video excerpt from NOVA, find out how whole genome sequencing saved the life of Alexis, a fraternal twin who was originally diagnosed with cerebral palsy but, in fact, had an even rarer genetic condition.

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 Nature, crabs face numerous obstacles in their migration from their forest home to the Caribbean Sea.

Botanists and biologists work to create a DNA barcode library for plant life in this video segment from New York Voices.

Students learn how DNA fingerprinting has been used in criminal investigations and discuss the limitations of and problems with DNA testing.

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.

Learn about the Dance Theatre of Harlem is this segment from A Walk Through Harlem.

In this video from KQED's QUEST, find out how researchers have engineered a stove that is helping women in refugee camps in Darfur, Sudan.

A third grade class in Wuhan province, China holds debates for the election of class monitor in this segment from Independent Lens.

In this video segment from Africa, Flora explains why she is content to return to the bush.

In this video from Wide Angle, learn about the farmers of Vidarbha in central India who have seen a loss in profits due to the high cost of borrowing money and the low prices for their crops in a globalized market.

In this video segment adapted from Navajo Technical College, meet a dendroclimatologist who studies the relationship between precipitation and tree growth in the Navajo Nation.

In this visualization adapted from the University of Massachusetts Medical School, discover the role that dengue viral proteins play in a human cell as the virus prepares to replicate.

A 1967 federal court order resulted in this document, which mandated school desegregation in Birmingham.

This video segment from NOVA: A Desert Place describes the physical characteristics and organisms that define the desert biome.

In this video from Nature, observe elephants trek across the desert to an isolated waterhole.

In this video segment adapted from ZOOM, cast members make a bridge from a single piece of paper. Will it be strong enough to hold a hundred pennies?

This video from Nature offers a description of desirable traits in beef and dairy cattle.

In this video from Wide Angle, learn about the conditions that have caused some Zimbabweans to leave their homeland for Botswana.

In this video from NOVA scienceNOW, learn how scientists detect potential signs of life on distant planets.