In this visualization adapted from the University of Massachusetts Medical School, discover the role that dengue viral proteins play in a human cell as the virus prepares to replicate.

This video segment from NOVA: A Desert Place describes the physical characteristics and organisms that define the desert biome.

In this video segment adapted from ZOOM, cast members make a bridge from a single piece of paper. Will it be strong enough to hold a hundred pennies?

This video from Nature offers a description of desirable traits in beef and dairy cattle.

In this video from NOVA scienceNOW, learn how scientists detect potential signs of life on distant planets.

Students practice data collection by gathering data within the classroom on common causes of allergies. They examine and interpret data charts on national trends in allergies.

This video segment from Greater Boston examines whether environmental toxins may be to blame for a rare skin disease.

In this video segment from Nature, learn about six different breeds of cattle.

In this segment from Curious, learn about creating energy from solar rays to meet the growing energy needs of the world.

The CyberSquad tracks Digital position in time and then studies graphs to figure out what Hacker is scheming in this video from Cyberchase.

In this interactive activity from the Building Big Web site, think like an engineer and use your knowledge of dome design to match the right type of dome to the right location in a fictitious city.

This video segment from NOVA: "The Shape of Things" follows the growth of a duck embryo, from a single fertilized egg cell to a complex, hatching duckling.

In this video profile produced for Teachers' Domain, meet teacher Dustin Madden, an IŰ__ŒóíŠupiaq who hopes to inspire students to take an active role in protecting the natural environment by giving them a foundation in math and science.

In this video produced by ThinkTV, explore the effects of land masses on local climate conditions, and learn about regional impacts of land-atmosphere interactions.

In this video segment adapted from NOVA scienceNOW, scientists examine the link between rising sea surface temperature and more intense hurricanes.

In this media-rich lesson, students learn how global warming is changing the Alaskan environment and examine the consequences of climate change on the region's human and wildlife inhabitants.

Students model, build, and draw diagrams of electric circuits and test the conductivity of a variety of materials.

In this animation produced by WGBH and Digizyme, Inc., see how molecules of DNA are separated using gel electrophoresis, and how this process enables scientists to compare the molecular variations of two or more DNA samples.

Scientists discuss whether or not endocrine disrupting chemicals, which may cause birth defects and other health concerns, should be controlled in the absence of conclusive proof, in this video segment adapted from FRONTLINE: Fooling with Nature.

Watch students as they conduct an energy audit on a home and gain hands-on experience for a career in the green energy industry, in this video adapted from ATETV.