Learn & explore

Looks at how human activities have affected Earth's environment over the course of the twentieth century, discussing climate, global warming, deforestation, endangered species, environmental pollution, and other topics, and explores the need to establish new policies and practices for interacting with and using natural resources.

Explores scientists' evolving perception of the solar system, discussing the eight chief planets, dwarf planets, and Pluto, presenting photographs and illustrations of planets, comets, asteroids, and other bodies in space, and including a list of further resources.

Provides information about voyages of exploration and discovery around the world since ancient times and includes biographical details about explorers as well as maps, illustrations, and photographs.

Explores scientists' evolving perception of the solar system, discussing the eight chief planets, dwarf planets, and Pluto, presenting photographs and illustrations of planets, comets, asteroids, and other bodies in space, and including a list of further resources.

Contains articles that provide information about the life, career, and administration of each of the men to serve as U.S. president, from George Washington to Barack Obama, and includes profiles of the first ladies, as well as essays on presidential duties, the election process, the Cabinet, the White House, and related topics.

Contains articles that provide information about the life, career, and administration of each of the men to serve as U.S. president, from George Washington to Barack Obama, and includes profiles of the first ladies, as well as essays on presidential duties, the election process, the Cabinet, White House, and related topics.