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.

In this video segment adapted from the International Institute for Sustainable Development, Inuit observers describe how their traditional understanding of weather patterns is being challenged by unpredictable weather behaviors.

How can you pick up an ice cube with a string? Watch this video segment adapted from ZOOM to see how salt can help.

This video adapted from the University of Leicester demonstrates the proper use of different-sized micropipettes to measure precise volumes of liquid in the lab.

In this lesson designed to enhance literacy skills, students examine our growing waste problem and learn about strategies we can use to lessen the strain on our landfills and Earth's natural resources: reduce, reuse, recycle.

This video segment adapted from Texas Parks and Wildlife Department explores the role of the wetlands in our environment, including providing habitats for wildlife, acting as natural water filters, and playing a part in the greater water cycle.

Take control of a virtual car and learn how vectors are used to represent velocity and acceleration in this interactive activity developed for Teachers' Domain. Grades 6-12.

In this ZOOM video segment, cast member Francesco follows the paper trail to find out what happens to his recyclables. He visits a material recovery center and learns how paper is recycled and the number of trees that are saved as a result.

In this adapted video segment, ZOOM guest Laura shows us some of the natural features of Yellowstone National Park, including geysers, hot springs, fumaroles, and mud pots, as well as some of the wildlife.

This interactive resource adapted from the National Park Service illustrates the difference between explosive and effusive volcanic eruptions as well as the hazards that can result, including lahars, tsunamis, and lava flows.

This interactive resource adapted from the National Park Service illustrates the variety of landforms and features created by volcanoes. Featured are calderas, craters, fumaroles and other geothermal features, igneous rocks, lava flows, lava tubes, and maars.

In this video, students learn that the Exxon Valdez oil spill in Alaska in 1989 was not the sole cause of the decline of species in the local ecosystem. Rather, an explanation is posited for why some animal populations were already in decline when the spill occurred. Many of these animals share a common food: the sand lance, a fish whose populations have shrunk with the steady rise in ocean temperature that began in the late 1970s.