In this interactive activity adapted for grades 3–5 from Annenberg Learner’s Teaching Math Grades 6–8, use virtual Cuisenaire® Rods to represent fractions and to perform operations with fractions.

In this interactive activity from ChemThink, learn about covalent molecules and how the VSEPR theory predicts the shapes of covalently-bonded molecules.

This video segment follows neurophysiologist Allen Counter as he studies an epidemic of hearing loss in Moriussaq, Greenland, one of the quietest places on Earth. Footage from NOVA: "Mystery of the Senses: Hearing."

This video segment adapted from NOVA relates the dramatic story of vulcanologists trying to predict the timing of the cataclysmic eruption of Mount Pinatubo in the Philippines.

This interactive activity adapted from A Science Odyssey Web site helps you visualize different types of plate tectonic activity and shows the impact this activity has on Earth's surface.

In this lesson designed to enhance literacy skills, students examine how to multiply fractions by whole numbers in the context of a recipe.

Join a group of middle-school students on a visit to a laboratory at the Massachusetts Institute of Technology, where they experiment with "mystery mud" and learn about the relationships between magnetism, particle motion, and changes in the state of matter.

In this video adapted from NOVA scienceNOW, find out about the discovery of a new building material, the carbon nanotube, whose physical properties could theoretically enable the creation of a 22,000-mile elevator to space.

In this video segment adapted from Haskell Indian Nations University, student filmmakers explain why it is important to them to make a video about climate change.

In this video segment adapted from Navajo Technical College, meet two members of the Navajo Nation, one Elder and one scientist, as they share their observations about how precipitation has changed since they were children.

In this lesson designed to enhance literacy skills, an early astronaut's experiences teach students that Newton's third law of motion—for every action, there is an equal and opposite reaction—applies both on Earth and in outer space.

In this video segment adapted from NOVA, NASA learns hard lessons from the first American attempt to do work while "walking" in space. The video also explores Newton's third law of motion.

In this video segment adapted from NOVA scienceNOW, MIT engineer Dava Newman is working to replace today's bulky, inflated space suits with a radical, sleek design that may one day allow astronauts to walk easily on Mars.

Coral reefs are often portrayed as brightly lit, bustling underwater marvels full of colorful creatures. This video segment, adapted from NOVA, paints a different picture as it explores the nocturnal behavior of organisms in the reef.

This video segment adapted from the NOW-RAMP 2002 Expedition documents a research expedition to Nihoa Island. It showcases Nihoa's unique birds and plants, the threat posed by invading grasshoppers, and restoration efforts.

Nitrogen, one of the most abundant elements in the universe, is essential to life. This interactive activity adapted from the University of Alberta provides an overview of the nitrogen cycle.

This video segment adapted from FRONTLINE looks at nuclear fission as an energy source that can be used to generate electricity.

In this lesson designed to enhance literacy skills, students examine the nutritional content of different foods and learn about the health benefits and risks associated with the food choices they make.

Perform a virtual heart transplant in 19 easy steps with this interactive feature from the NOVA: "Electric Heart" Web site.

This video segment produced for Teachers' Domain features a time-lapse video of clouds forming, changing, and moving across the sky.