Beringia: The land between Siberia and Alaska that was exposed only during the Ice Age.

Land Bridge: During the ice age the first settlers of the Americans migrated across a large stretch of land  connecting Asia and North America.  As the climate warmed, glaciers melted, sea levels began rising, and by 11,600 years ago, the Bering Land Bridge disappeared beneath the Bering Strait.

Ice Age:  Between 20,000 and 40,000 years ago, sheets of ice covered great portions of the world 

Adaptation: The changes creatures make to increase and support their ability to survive in new conditions.

Migration: To move from one region or country to another.

Megafauna: The large-bodied animal species during the Pleistocene, like the giant sloth, mammoth, and mastodon that became extinct about 10,000 years ago.

Climate: The pattern of weather over a long period of time.

Tundra: A cold treeless area with permanently frozen subsoil. Vegetation is limited to mosses, and small shrubs

Subarctic: Also called boreal or subpolar, this climate has freezing in winters to −40°F, and cool but short summers; only melting a few feet of ice on the ground, maintaining the permafrost

Archaeologist: A person who studies past human cultures through the objects they have left behind. 

Clovis: The type of stone spear point made by people of the Americas about 11,500 years ago. 

Paleoarctic People: The first people of the Americas who crossed the Beringia Land Bridge