How do floods and fireschange the land?You have learned how erosion and depositionchange the land slowly. What causes Earth’ssurface to change quickly?FloodsHeavy rain or quickly melting snow can causewater to flow over the land....

What is in the air?When you think of wind, what comes tomind? Wind is really just air in motion. In fact,air surrounds Earth like a thin blanket. Thisblanket of air is the atmosphere (AT•muhs•feer).GasesThe...

Why does water change state?Water moves from Earth’s surface into theatmosphere. Then it moves back to the surface.Water changes state as it moves. Water cycle diagram EvaporationWater seems to disappear when it evaporates(ee•VAP•uh•rayts). Evaporation...

What is climate?The weather where you live may change fromday to day. Yet you can predict what the weatherwill be like each season. The pattern of seasonalweather that happens year after year is calledclimate...

What are air masses and fronts?The wettest place on Earth is in the state ofHawaii. Rain falls over one of the islands about350 days of the year. One of the driest placesin the world...

Matter is anythingthat has mass and takes up space.Most things are made of matter. The air youbreathe and the book you are reading are madeof matter. Light and heat are not matter, however.They do...

How do we measure matter?Measuring and counting squares is oneway to compare size. When we measure,we use standard units. A standard unit is ameasurement on which people agree. Manypeople in the United States use...

What are elements?People once thought that all matter wasmade up of earth, air, fire, and water. We nowknow that all matter is made of elements(EL•uh•muhnts). An element is a substance thatis made up of...