In Blazing a Genetic Trail, by the Howard Hughes Medical Institute, follow this three-step approach to treating genetic diseases.

This video segment from NOVA: "Cracking the Code of Life" looks at one of the key players in the race to decode the human genome.

This video segment from NOVA: "The Killer's Trail" investigates the potential for DNA evidence to solve murder cases, even those from the distant past.

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.

This video segment from NOVA: "Sea Behind the Dunes" tracks the return of spawning alewife fish from the open ocean back to the freshwater streams and ponds where they were born. [3:34]

This interactive feature from the NOVA: "Leopards" Web site presents a wide variety of ways in which animals use coloration to their advantage.

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."

Fevers are a sign of infection, but they may also be part of the cure. This drawing illustrates Matthew Kluger's lizard study, which supports the notion that fever can be beneficial.

This video segment from NOVA: "The Mystery of Animal Pathfinders" explores how the migratory patterns of shorebirds have evolved to coincide with the spawning of horseshoe crabs. [6:00]

This video segment explores the sense of taste in humans -- why we have it, and what happens when we lose it. Footage from NOVA: "Mystery of the Senses: Taste." Includes background reading material and discussion questions. [4:18]

Why do teenagers act the way they do? This video segment from FRONTLINE: "Inside the Teenage Brain" explores the work scientists are doing to explain some of the mysteries of teenage behavior.

This video segment explores the role of touch in the development of young animals, including humans. Footage from NOVA: "Mystery of the Senses: Touch." [2:57]

Background image of normal disc-shaped red blood cells from the University of Utah. Inset shows sickled red blood cells, curved and rigid, from the Virginia Medical College.

This feature from the NOVA: "Cut to the Heart" highlights facts about the heart, including its size and placement, and will help you to understand the importance of this wondrous organ in our bodies.

This video segment from NOVA: "Animal Imposters" shows the lightning-fast strike of the anglerfish. [1:30]

This collection of images of ten different birds illustrates the diversity of bird beaks.

This interactive feature from the NOVA: "Surviving Denali" Web site details the variety of ways the body can fail while climbing a high-altitude peak.

Which part of your brain controls your ability to swallow? Your instinct to survive? And how do all the brain's parts function cooperatively? Find out with this interactive feature from the NOVA: "Coma" Web site.

This video segment describes the basics of the circulatory system: how the heart pumps the blood that carries oxygen and nutrients throughout the body. [3:14]

This video segment explores the integral relationship between structure and function in snakes.

Why do cows chew their cud? This video segment from Secret of Life: "Accidents of Creation" describes the physical adaptations that have made ruminants some of the most important, and certainly the most efficient, plant eaters on earth.

This collection of images shows several types of plant seeds, each with a different mechanism for dispersing from the parent plant.

This diagram from Rainbird Publishing describes the specialized physical characteristics that allow woodpeckers to create some of the most secure nests in the bird world.

Through flashback, L.D.Cox tells how he survived the sinking of the U.S.S. Indianapolis during World War II in this segment from History Detectives.