In this feature, adapted from Interactive NOVA: "Earth," students explore the relationship between oxygen concentration and the well-being of various organisms by simulating a change in oxygen levels and observing what happens.

In this interactive activity from ChemThink, take a closer look at atomic structure, properties, and behaviors.

This video segment adapted from A Science Odyssey takes a look at the scale of the atom and the tremendous amount of space between the electrons and the nucleus. If all this empty space exists in matter, how can any substance be solid?

Novel representations and diverse perspectives can reveal new insights into complex systems, and can support rich understandings of the world. In this activity, students will identify and analyze the choices artists and scientists make when creating representations of living or non-living natural objects. This process will help students recognize the potential and place for their own articulation of how the world works. After drawing from nature, students will reflect on the process of representing information, then compare their drawings with that of a 16th-century artist. Students will consider what is included and what is excluded, and hypothesize about larger contexts and systems.

The engineering design process involves many steps. Not only must an engineer be able to devise a solution to a problem, he or she must also be ready to test and evaluate that solution to reach the best result. To successfully complete the design process, an engineer must be able to identify design flaws and learn from his or her mistakes. In this video segment adapted from ZOOM, learn about the design process as cast members create automatic door openers that enable them to open their bedroom doors while lying on their beds. For grades 3-8.

The impact of natural disasters is made vivid in this video segment adapted from NOVA. A small town in Iceland, prepared for recurrent avalanches, is devastated when one takes a new and damaging path.

Students explore static electricity by rubbing a simulated balloon on a sweater. As they view the charges in the sweater, balloon, and adjacent wall, they gain an understanding of charge transfer. This item is part of a larger collection of simulations developed by the Physics Education Technology project (PhET). The simulations are animated, interactive, and game-like environments.

In this video from DragonflyTV, Jai and Jonathan track, graph, and analyze the motion of basketball shots as they investigate what factors influence the accuracy of their game.

This video segment from the Nevada Department of Wildlife looks at various species of bats and how they impact the environment.

Look inside a resistor to see how it works. Increase the battery voltage to make more electrons flow though the resistor. Increase the resistance to block the flow of electrons. Watch the current and resistor temperature change.

This Nature video segment focuses on the four foods most important to the grizzly bears' survival, and it describes the threats to the supply of each of them.

In this video segment from Nature, learn about the problems bears are creating on ranch land surrounding Yellowstone National Park.

This Nature video segment explores how the relationship between humans and grizzly bears has changed over the course of American History, and it describes the closing of the Yellowstone National Park garbage dumps in the 1970s.

Learn about the precautions humans must take in the face of a growing grizzly bear population in this video from Nature.

This video segment explores the world of the beaver, including the biology of the species and, more importantly, its ability to transform an ecosystem for its own benefit.

This video segment describes how the Australopithecus afarensis skeleton known as Lucy could have been fossilized. Footage courtesy of NOVA: "In Search of Human Origins."

This video segment from NOVA: "The Mystery of Animal Pathfinders" explores honeybee communication and navigation.

Cocos Island, a remote volcanic summit in the middle of the Pacific Ocean, serves as a beacon for hungry predators, including thousands of hammerhead sharks that travel here each year in search of prey. This video segment from NOVA: "Island of Sharks" depicts some of the common predator-prey interactions that take place in the nutrient-rich waters surrounding the island.

In this video segment adapted from NOVA scienceNOW, scientists discuss their attempts to grow human body parts in a jar.

This video segment from Evolution: "Extinction!" shows the impact of invasive species on native ecosystems.