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.

Examine how the human/grizzly relationship has changed since the closing of the Yellowstone dumps, and also learn about the challenges posed to both humans and bears, in this video segment from Nature.

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 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 graphic from Biology by Kenneth R. Miller and Joseph Levine suggests how some recent hominid fossil finds might fit into the overall picture of hominid evolution. As more fossils are found and further analysis advances our understanding of human evolution, this picture will almost certainly be revised.

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 from Wide Angle, visit a makeshift night school in rural India designed to allow child laborers who work during the day to obtain an education.

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