This video segment from Wild Europe: "Wild Arctic" explores the struggle for survival in one of Earth's most extreme environments.

This video segment adapted from NOVA features a variety of scientific perspectives on the age old question, "Are we alone in the universe?" Animations make vivid the improbability that we could intercept a radio wave signaling extra terrestrial intelligence.

After researching the characteristics of arthropods, students observe arthropods in the field, analyze their data, and learn how to develop their own arthropod collection. The unit is designed to be completed in eight or more sessions. The comprehensive curriculum materials contain information for teachers, including activity tips and an overview of the characteristics that define arthropods.

In this Biodiversity Counts activity, students use their arthropod knowledge to create and play a classroom Jeopardy-style game. The printable five-page PDF handout includes a series of inquiry-based questions to help students identify what they already know about arthropods and step-by-step directions for developing Jeopardy-style quiz questions.

This unit, in which students prepare to observe arthropods in their field site's different microhabitats, helps set the stage for a discussion on the ramifications of habitat loss. It's designed to be completed in four or more sessions and has comprehensive curriculum materials for teachers, including activity tips and an overview of the microhabitats in a temperate forest. The unit is designed to answer the following two target questions. What microhabitats exist at our site? Do different arthropods occur in different microhabitats?

This video segment explores the benefits and pitfalls of cloning as a means of reproduction. From Evolution: "Why Sex?"

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 the open ocean around the Bahamas, pods of wild Spotted Dolphins frolic in the sunshine. Sometimes, they get bored and approach boats. In this educational video, Jonathan joins dolphin expert Wayne Scott Smith to learn how dolphins interact with each other. Jonathan learns how to play the Bandana Game, a game of -keep away- that the dolphins invented and like to play with Scott. Please see the accompanying study guide for educational objectives and discussion points.

In the master-equation formalism, a set of differential equations describe the time-evolution of the probability distribution of an ensemble of systems. This can be used, for example, to describe the varied mRNA copy numbers found in individual cells in a population.

The stochastic simulation algorithm (SSA, Kinetic Monte Carlo, Gillespie algorithm) produces an example trajectory for a particular member of a probabilistic ensemble by looping over the following steps. The current state of the system is used to determine the likelihood of each possible chemical reaction in relative comparison to the likelihoods for the other possible reactions, as well as to determine when the next reaction is expected. Pseudo-random numbers are drawn to "roll the dice" to determine exactly when the next reaction will proceed, and which kind of reaction it will happen to be.

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

This OLogy activity shows kids that there are simple, but very helpful things they can do to protect the ocean, even if they live nowhere near the water. It has a checklist of 14 ways kids can be ocean helpers that includes asking for tap water instead of bottled water and leaving plants and animals where they find them. For each of the checklist items, kids can check either "I am doing this" or "I could do this."

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.