Georgia Performance Standards Framework for Covered with Water 6 th Grade Subject Area: Science Grade: 6

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1 One Stop Shop For Educators The following instructional plan is part of a GaDOE collection of Unit Frameworks, Performance Tasks, examples of Student Work, and Teacher Commentary. Many more GaDOE approved instructional plans are available by using the Search Standards feature located on GeorgiaStandards.Org. Subject Area: Science Grade: 6 Standards (Content and Characteristics): S6E3 Students will recognize the significant role of water in Earth processes. a. Explain that a large portion of the Earth s surface is water, consisting of oceans, rivers, lakes, underground water, and ice. b. Relate various atmospheric conditions to stages of the water cycle. S6CS1 Students will explore the importance of curiosity, honesty, openness, and skepticism in science and will exhibit these traits in their own efforts to understand how the world works. a. Understand the importance of and keep honest, clear, and accurate records in science. S6CS5 Students will use the ideas of system, model, change, and scale in exploring scientific and technological matters. a. Observe and explain how parts are related to other parts in systems such as weather systems, solar system, and ocean systems including how the output from one part of a system (in the form of material, energy, or information) can become the input to other parts (e.g., El Nino s effect on weather). b. Identify several different models (such as physical replicas, pictures, and analogies) that could be used to represent the same thing, and evaluate their usefulness, taking into account such things as the model s purpose and complexity. S6CS6 Students will communicate scientific ideas and activities clearly. c. Organize scientific information using appropriate tables, charts, and graphs, and identify relationships they reveal. S6CS8 Students will investigate the characteristics of scientific knowledge and how it is achieved. a. When similar investigations give different results, the scientific challenge is to judge whether the differences are trivial or significant, which often requires further study. Even with similar results, scientists may wait until an investigation has been repeated many times before accepting the results as meaningful. Enduring Understanding: Water occurs on Earth in three basic states: liquid, solid (ice) and gas (atmospheric moisture). Climate conditions, especially temperature and humidity, determine the amount and state of the water that reaches the land surface. Approximately 71% of the Earth's surface is covered by liquid water, while approximately 3% is covered with ice. Less than 1% is covered with freshwater. Most of Earth's water is located in the oceans as saltwater (over 97%); while lesser amounts are found in atmospheric moisture, glacial ice, lakes, streams and groundwater. July 2008 Page 1 of 10

2 The cycling of water in and out of the atmosphere plays and important role in determining climatic patterns. Water evaporates from the surface of the Earth, rises and cools, condenses into rain or snow, and falls again to the surface. The water falling on land collects in rivers and lakes, soil, and porous layers of rock, much of it flowing back into the ocean. Essential Questions: How much of the Earth is covered by each of the following: saltwater, ice and freshwater? Why is Earth's water constantly in motion? What are the most important sources of water for human use? What are the forces that drive the water cycle? Pre-Assessment: Students should answer the following: 1) Name the three phases or states in which water occurs on Earth., and 2) Estimate how much of the Earth is covered by each of the following: oceans and seas: lakes, rivers and streams: glaciers: 3) What percentage of the Earth's water is found in each of the following: saltwater in oceans and seas: freshwater in lakes/rivers/streams: water in soil and rocks (groundwater): ice in glaciers: 4) Does Earth's water move or circulate between these areas? (yes or no) 5) What is the most important form of energy that causes water to move or circulate between the oceans, atmosphere and land surface? July 2008 Page 2 of 10

3 ADMINISTRATION PROCEDURES Outcome / Visual estimates of the percentage of Earth's surface covered by oceans, glaciers, Performance freshwater lakes and rivers will show that most of Earth's water occurs as Expectations: saltwater. The student will realize that large areas of the continents are covered by ice; whereas, freshwater lakes and rivers make up a much smaller percentage. Students will understand that the water cycle is driven by solar heating and that climate determines the distribution of the different forms of water. The students will understand that freshwater used in homes and industry comes mostly from streams, lakes, and groundwater. It is important that the students realize that these water supplies are changing and very limited in volume. General Teacher Instructions: Background Knowledge for Teacher: Water occurs on Earth in three basic forms: liquid (water in oceans, rivers and groundwater), solid (ice in glaciers), and gas (atmospheric moisture or humidity). The distribution of Earth's water can be studied using world maps. Saltwater oceans and seas cover a large portion of the Earth (approximately 71%). Land cover without ice accounts for approximately 26%, while land covered with ice accounts for about 3% of Earth's surface. Lakes, ponds, swamps, streams, and rivers account for less than 1% of the surface area. It is therefore obvious that after saltwater, ice is the second most abundant form of water on Earth. Freshwater in lakes and rivers is much less abundant than saltwater and ice. In order to make accurate estimates of the volumes and percentages of saltwater, freshwater and ice, area calculations must be converted to volume measurements. Average depths of the oceans and lakes are needed in combination with average thickness of glacial ice. Extensive evaporation in the warm tropical and subtropical seas adds much of the atmospheric moisture of the hydrologic cycle. Uneven heating of the Earth's surface and rotation of the Earth on its axis form winds that aid in this evaporation and help transport this moisture-rich (humid) air. Glacial ice forms in colder regions (polar regions and mountainous areas) as moisture is carried from the evaporated salt and freshwater sources and precipitated as snow. Lakes and rivers are also formed by precipitation of ocean-derived moisture. Evaporation, condensation and precipitation are the dominant processes that form the water cycle and determine the distribution of Earth's water. Global warming and cooling result in significant changes in water cycle processes and the surface distribution of Earth's water supply. Because the oceans are extremely shallow (average depth is 4 kilometers) relative to their size, the addition of water from melted glaciers or the removal to form extensive glaciers during the Ice Ages can cause a significant change in sea level. Instructions for Teacher: 1. Print several color copies of the provided 'Different Views of the Earth' or display the images using a color transparency or computer projector. A classroom world globe showing land cover could also be used in place of the color diagrams. July 2008 Page 3 of 10

4 2. Make copies and distribute the provided worksheet to each student. 3. Explain to the class the difference between a liquid, solid and gas. This should be explained before the start of the lab. Explain how liquid water occurs as both saltwater and freshwater. Atmospheric water is usually not seen unless it becomes dense enough to form small droplets resulting in the formation of clouds and fog. You should also provide a definition of a glacier (a mass of ice formed by compacted snow that is thick enough to flow). The two largest glaciers are the Antarctica and Greenland ice sheets (glaciers that cover most of a continent) that are clearly visible on the polar views of Earth. 4. Handout calculators for the students to check their surface area percentages and make sure they add up to 100%. Explain to the students that they should first make their estimates, then adjust these estimates so that they total 100%. They will also need calculators to determine the percentage of the Earth's water that is found as saltwater, freshwater and ice based on the data provided in a worksheet chart. 5. Compare and contrast the map used in question 4 to the Earth images used in question 5. Explain that flat maps of the Earth commonly distort the sizes of the continents and oceans especially near the poles. Also show how color Earth images or maps are needed to better distinguish areas covered with ice. Also explain how the oceans are very shallow for their size. They average only 4 kilometers in depth, while they are commonly thousands of kilometers across. Explain how melting or expansion of the ice caps and glaciers causes water levels in the oceans (sea level) to rise or fall. Materials Color copies of the provided 'Different Views of the Earth'. (Note: Instead of Needed: making color copies, a color transparency and overhead projector or digital copies of the figures and a computer projector can be used to display the figures. A classroom globe can also be used if it shows land and water cover.) Copies of the provided worksheet for each student Calculators Colored pencils or crayons Safety Precautions: None required. Task with Student Directions: See attached worksheet. July 2008 Page 4 of 10

5 Resources: U.S. Geological Survey 'Water Cycle Website: EPA's Water Information Website for Kids: Georgia Water Conservation Website: Georgia Public Broadcasting Digital Library: NASA's Earth Observatory Website Homework / Extension: Assign different components of the water cycle for the students to research. This should include: stream flow, surface runoff, groundwater movement, glacial movement, ocean currents, and atmospheric movement. Also have them define the following terms: evaporation, precipitation, condensation, groundwater, glacier, and water cycle. Advanced Learners: Have the student research the Ice Ages. During these periods of cooler global temperatures, glacial ice covered nearly 30% of the land surface or approximately 9% of the Earth's surface. Ask the students to discuss how global warming would change the amount and distribution of Earth's water resources. Next, have the students describe which water cycle processes would increase or decrease during global cooling. In contrast, have the students discuss how global warming would change the water cycle and global sea level? July 2008 Page 5 of 10

6 Different Views of the Earth Figure 1. Earth view at equator and 0 longitude. Figure 2. Earth view at equator and 180 longitude. Figure 3. Earth view at South Pole. Figure 4. Earth view at North Pole. (Images generated using ESRI ArcGlobe Version 9.2 software and data.) July 2008 Page 6 of 10

7 Name 1. Label the various forms of water found on Earth with the basic state in which it occurs (solid, liquid or gas). Ice: Ocean water: River water: Rain: Snow: Groundwater: Humid air in atmosphere: 2. Draw lines between the different forms of water and the conditions under which they form. Next, draw lines between the temperatures and the locations on the Earth where these temperatures are most common. Please note that the low latitudes are areas near the equator that receive more sunlight than other regions because this part of the Earth is closest to the sun. The polar regions receive the least amount of sunlight and solar heating. The middle latitudes are midway between the equator and the polar regions. Ice High Temperatures (hot) Polar Regions Water Low Temperatures (cold) Low Latitudes Humid Air Intermediate Temperatures Middle Latitudes 3. Using the information from question #2, describe how climate, especially average temperatures, determine which form of water occurs at different locations around the world. Give examples. July 2008 Page 7 of 10

8 4. Using the Map of the World shown below, estimate the amount of the Earth that is covered by oceans and seas. Next estimate the amount covered by land. The two numbers should add to 100%. Amount covered by oceans/seas: % Amount covered by land: % Total amount: % Equal Angle Map of the World. (Generated using ESRI ArcMap Version 9.2 software and data.) 5. A much better description of Earth's surface can be obtained by using the more realistic views of the Earth that are provided by your teacher. Using the images of Earth provided by your teacher, estimate the amount of Earth covered by saltwater (oceans and seas), freshwater (lakes and rivers), ice (glaciers) and land without ice. Your estimates should add up to 100% because you are describing all of Earth's surface. So after making the estimates, use a calculator and add up the values and if they don't add to 100%, adjust the estimates until they do. Saltwater Cover (oceans and seas): % Freshwater Cover (lakes and rivers): % Land with Ice Cover (glaciers): Land without Ice Cover: % % Total: % 6. In the last question you estimated the area of the Earth covered by saltwater, freshwater and ice. What other data is needed to determine the volume of water found on the Earth as either saltwater, freshwater or ice? July 2008 Page 8 of 10

9 7. The chart shown below provides estimates of the percent of Earth's water that is found on Earth in the different forms discussed in the first part of this lab. Using this data, answer the questions shown below. Water Source Form Percent of Earth's Water Ocean and Seas Liquid - Saltwater Glaciers Solid - Ice Groundwater Liquid - Freshwater.625 Lakes, Rivers & Streams Liquid - Freshwater.016 Atmosphere Gas - Atmospheric Moisture.001 a) What percentage of Earth's water is saltwater that is unsuitable for land plants and animals including humans b) What percentage of Earth's water is freshwater? (Hint: Add the percentages found in all of the other water sources or subtract the percentage found in oceans and seas from 100.) c) Why is most of the Earth's freshwater not available for human use? d) Groundwater and lake and river water are the most important sources for humans. What percentage of Earth's water is found as groundwater and river and lake water? e) Why is freshwater considered such a valuable and limited natural resource even though approximately 74% of the Earth's surface is covered with water or ice? 8. Solar energy or heating provides much of the energy that drives the water cycle. Heating in warm climates causes evaporation or change of surface water to atmospheric moisture (humid air enriched in water gas). Unequal heating of the Earth's surface and rotation of the Earth on its axis form winds that move this moisture. In which of the following areas would evaporation be most important: cold polar regions, warm desert areas, cold ocean areas, or warm ocean area? Explain. 9. Gravity brings water back to the land surface and oceans. Describe how gravity continues to move the water after it reaches the land surface. How does this movement of water on land help reshape the land surface? July 2008 Page 9 of 10

10 GRAPHING THE DISTRIBUTION OF EARTH S WATER Name If the container shown below represents all of the earth s water, color the diagram according to the percentages of the different components shown below: Oceans/Seas: 97.25% (light green) Color all of the large 1% boxes and the one.25% box that is not subdivided. Label these as saltwater. Groundwater:.625% (light blue) Color ten of the.0625% size boxes that are not subdivided into smaller boxes. Label these as freshwater. Rivers, Streams and Lakes:.016% (light brown) Color one of the smallest.016% boxes. Label this as freshwater with the label off to the side and an arrow to the box. Glacial Ice: 2.108% (white.) After all of the above components are colored, there should be two large 1% subdivided boxes and seven of the smallest.016% boxes that are not colored. These will represent glacial ice, so leave them white and label them ice. 1% Block.25% Block.0625% Block.016% Block July 2008 Page 10 of 10