GEOGRAPHY
"If it's about Earth's land, water, air, or living things-- particularly people-- it's geography. The word comes from the Greek "geo," which means "earth," and "graphy," which means "writing or description." Physical geographers study landforms, water, soil, climate, and the distribution of living things.

OCEANS
"If aliens tried to land a spaceship on earth, they would more likely land with a splash than with a thud. That's because more than two-thirds of our planet's surface is covered by water. We have many different names for the areas of water that cover the earth. We call them ponds, lakes, streams, rivers, seas, and oceans. The biggest ones are the oceans, and there are five of them: the Atlantic,. . . "

ECOLOGY
"That's the first step in ecology-- looking around. Your house, for instance, is an ideal place to start. It's perfect for a big mammal like you. Yet, it's also home to spiders, insects, and maybe the occasional mouse. Just outside are birds, squirrels, frogs, grasses, trees, flowering plants, rocks, dirt, and even more insects. When you look around at living things and their environment, you are. . . "

EARTH
"Spread out a map of the world. What you see on its depends on the kind of map you have. Does it show cities and countries? Mountains and valleys? Maybe weather patterns? The variety of features is so great that one map just can't handle it all. Earth is part of a nine-planet solar system within the Milky Way galaxy. Its size and location aren't very impressive. We inhabit the third planet. . . "

VOLCANOES
"Volcanoes are like sleeping giants. After years, even centuries, of rest, they awake. They erupt. Some powerful eruptions blow tops off mountains, flatten forests, and dam up rivers. Some eruptions have killed tens of thousands of people. A few have buried cities, while others have buried mountains. Some big eruptions have even changed the world's weather for years. Volcanoes also shape the earth.. . . "