This video from Religion & Ethics Newsweekly features Timbuktu, one of the most remote and inaccessible places on the planet and a former thriving center of Islamic learning.

This TV 411 segment features a lesson from Question Man on how to informally calculate 15% tips at restaurants.

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.

In this video segment from Cyberchase, the CyberSquad tries to reach Ms. Fileshare by using a 3 x 3 matrix to figure out the various ways they can travel to her.

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 video segment from Regents Review 2.0 uses a trigonometry equation to determine the height of a flagpole located in front of the school.

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

In this video segment from Cyberchase, Digit must a make a straight line between the two points and then follow the path created.

Jackie and Matt are looking at the same object along two different lines, in this video segment from Cyberchase.

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.

In this video segment from Cyberchase, Harry must adjust his dinner budget after his cousin, Harry, unexpectedly decides to join him on his date

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.

A variety of symbiotic relationships exist between sharks and other marine species in this segment from Nature.

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.

Using manipulatives, students figure out patterns in problems involving seating arrangements. They write algebraic equations to describe the relationships.