In this video adapted from Earth Island Institute, meet a high school student who educated her community about how a coal-burning power plant was contributing to asthma and other health problems there.

Why do teenagers act the way they do? This video segment from FRONTLINE: Inside the Teenage Brain explores the work scientists are doing to explain some of the mysteries of teenage behavior.

In this video adapted from Earth Island Institute's New Leaders Initiative, meet a high school student who worked to enact a state law to make cosmetics safer, after she learned they contained toxic chemicals linked to cancer.

Watch the ZOOM cast discover which insulator -- newspaper or aluminum foil -- is better at keeping an ice cube frozen longer.

In this video segment adapted from ZOOM, cast members show you how to make your very own electroscope. You can use it to find out if an object is electrically charged.

This illustration from Evolution by Monroe W. Strickberger shows the remarkable similarities between the bones in the forelimbs of various tetrapods, all of whose limbs serve very different functions.

This interactive activity from the NOVA Web site challenges you to think like Einstein and understand how time travel might be possible.

This video from NASA explains the process by which gamma-ray flashes associated with storms produce matter/antimatter particle pairs.

This illustrated essay from the NOVA Web site answers questions about irregularities in the tides.

In this lesson designed to enhance literacy skills, students learn that transitional fossils provide scientists with evidence to establish how major animal groups are related to one another.

This animation produced by WGBH and Digizyme, Inc. demonstrates the experimental technique used to introduce DNA plasmids inside bacterial cells, a process called bacterial transformation.

John Noble Wilford, a New York Times science writer, outlines various hypotheses on the origin of bipedalism.

In this video segment adapted from NASA, learn how engineers are transforming the future of flight by designing airplanes based on principles found in nature. In the early 1900s, the Wright Brothers found inspiration for their first airplane in nature. Their "Flyer," which was modeled on a bird's flexible wing design, was steered and stabilized by pulleys and cables that twisted the wingtips. Despite its success, this control strategy quickly vanished from aviation. Instead, stiff wings capable of withstanding the greater forces associated with increased aircraft weights and flying speeds became the standard. In this video segment adapted from NASA, learn how designs found in nature have inspired today's aerospace engineers as they conceive the next-generation of flying machines. Grades 3-12.

In this video segment from NOVA: Judgment Day: Intelligent Design on Trial, learn about the discovery of a well-preserved transitional fossil and how such transitional fossils support the theory of evolution.

Watch the ZOOM cast build a chair out of newspaper by making good use of the strength of triangles.

In this video segment adapted from ZOOM, the cast tries to design and build a bridge made out of drinking straws that will support the weight of 200 pennies.

This interactive activity, from the Building Big Web site, explores tunneling and the tools and methods used to do the job.

This video segment presents a variety of sounds -- from animals to machines to musical instruments -- while introducing the basic concepts of vibration, volume, and pitch.

The environment plays a critical role in shaping the evolutionary changes that organisms undergo. For animals, food is one of the most important components of the environment. This video focuses on snakes and some of the most important adaptations of these remarkable creatures.

In this lesson designed to enhance literacy skills, students examine how to use fractions to measure and help conserve freshwater resources.