Water on Earth PDF

# Lesson 1: Water on Earth ## Unlock the Big - Why is water important? - Where is water found? - What is the water cycle? ## My Planet Diary: How Much Water Do You Use? You take a shower. You brush your teeth. You take a big drink after soccer practice. All day long, you need water! How much...

# Lesson 1: Water on Earth ## Unlock the Big - Why is water important? - Where is water found? - What is the water cycle? ## My Planet Diary: How Much Water Do You Use? You take a shower. You brush your teeth. You take a big drink after soccer practice. All day long, you need water! How much water do you use in a day? How much do you think your whole state uses? The graph shows the water used per person in the ten states of the United States with the largest populations. The data include the water used for all purposes, including farming, industry, and electric power. **Study the graph. Then answer the questions below.** 1. In which state is the water use per person greatest? In which state is it least? 2. What do you think might explain the difference in water use between states? >**Planet Diary:** Go to Planet Diary to learn more about fresh water on Earth ## Science Stats: Water Use Per Person Per Day | State | Gallons Used per Person per Day | |---|---| | California | 1500 | | Texas | 1000 | | New York | 1000 | | Florida | 500 | | Illinois | 750 | | Pennsylvania | 500 | | Ohio | 500 | | Michigan | 750 | | Georgia | 500 | | North Carolina | 500 | *** # My Science Online **Vocabulary:** * Habitat * Groundwater * Water Cycle * Evaporation * Transpiration * Precipitation **Skills:** * Reading - identify the main idea * Inquiry - observe ## Why is Water Important? What do you and an apple have in common? You both consist mostly of water! Water makes up nearly two thirds of your body's mass. That water is necessary to keep your body functioning. * All living things need water in order to carry out their body processes. In addition, many living things live in water. **Body Processes** Without water, neither you nor an apple could survive. Water allows organisms to break down ford, grow, reproduce, and get and use materials they need from their environments. Animals obtain water by drinking it or by eating foods that contain water. Most animals cannot survive more than a few days without water. Plants and other organisms that make their own food also need water. Algae and plants use water, along with carbon dioxide and energy from the sun, to make their own food in a process called photosynthesis. Other organism get food by eating the plants, or by eating organisms that eat the plants. **Habitats** Water provides habitats for many living things. An organism's habitat is the place where it lives and obtains all the things it needs to survive. Some organisms cannot live out of water. You are probably familiar with large water-dwelling organisms such as sharks, but most such organisms are microscopic. In fact, aquatic, or water, habitats contain more types of organisms than land habitats do. ## Assess Your Understanding **Gotit?** * I get it! Now I know that living things use water. * I need extra help with... Go to My Science Coach online for help with this subject. ## Figure 1: The Need for Water Predict: Underline the sentence that explains why these animals need the water hole. What would happen if the water hole dried up? *** ## Where is Water Found? When you turn on the tap, it might seem that an endless supply of fresh water comes out! But Earth's freshwater supply is very limited. * Most of Earth's surface water — roughly 97 percent — is saltwater found in oceans. Only 3 percent is fresh water. * Of that 3 percent, about two thirds is frozen in huge masses of ice near the North and South poles. About a third of the fresh water is underground. A tiny fraction of fresh water occurs in lakes and rivers. An even tinier fraction is found in the atmosphere, most of it in the form of invisible water vapor, the gaseous form of water. **Identify the main idea in each paragraph on this page.** **Oceans** Find the oceans on the map in Figure 2. Pacific, Atlantic, Indian, and Arctic are the names used for the different parts of the ocean. (Some scientists call the area around Antarctica the Southern Ocean.) But the waters are really all interconnected, making up one big ocean. The Pacific Ocean is the largest, covering an area greater than all the land on Earth. The Atlantic Ocean is next largest, though the Indian Ocean is deeper. The Arctic Ocean surrounds the North Pole. Smaller saltwater bodies are called seas. **Ice** Much of Earth's fresh water is frozen into sheets of ice. Massive ice sheets cover most of Greenland and Antarctica. Icebergs are floating chunks of ice made of fresh water that break off from ice sheets. You could also find icebergs in the Arctic Ocean and in the North Atlantic. ## Do the Math: Analyzing Data These graphs show how much of Earth's water is found in different forms 1. **Read Graphs** Where is most water on Earth found? 2. **Read Graphs** About what fraction of Earth's fresh water is in the form of ice? 3. **Interpret Data** How does the total amount of groundwater compare to the total amount of ice? ## Figure 2: Earth's Major Waterways The map shows Earth's oceans and some major freshwater sources. **Classify: Circle the names of three saltwater sources. Underline the names of three freshwater sources.** ## My Science Online - Water Locations **Rivers and Lakes** Look at Figure 2. All the rivers and lakes marked on the map contain fresh water, as do many other smaller rivers and lakes. North America's five Great Lakes contain about 20 percent of all the water in the world's freshwater lakes. **Groundwater** To find some of the fresh water on Earth, you have to look underground. When it rains or snows, most water that doesn't evaporate soaks into the ground. This water trickles through spaces between particles of soil and rock. Water that fills the cracks and spaces in underground soil and rock layers is called groundwater. Far more fresh water is located underground than in all of Earth's rivers and lakes. ## Assess Your Understanding 1. **List** What are the four main sources of fresh water on Earth? 2. **Make Judgments** Which freshwater source do you think is most important to people? Why? **Gotit?** * I get it! Now I know that Earth's water is found in... * I need extra help with... Go to My Science Coach online for help with this subject.