Curriculum Guide. National Science Education Standards Grades 5-8 Earth and Space Science

Transcription

1 National Science Education Standards Grades 5-8 Earth and Space Science Curriculum Guide Structure of the Earth system: Global patterns of atmospheric movement influence local weather. Oceans has a major effect on climate, because water in the ocean holds a large amount of heat. - Deep ocean currents are caused by the density of ocean water. - The temperature, density, and color of ocean water varies. - Thermohaline circulation is the flow of water induced by differences in temperature (thermo) and salinity (haline). These differences in water properties lead to density differences. Grades 9-12 Earth and Space Science Energy in the Earth System: Heating of earth s surface and atmosphere by the sun drives convection within the atmosphere and oceans, producing winds and ocean currents. Global climate is determined by energy transfer from the sun at and near the earth s surface. This energy transfer is influenced by dynamic processes such as cloud cover and earth s rotation, and static conditions such as the position of mountain ranges and oceans. Geochemical Cycles The earth is a system containing essentially a fixed amount of each stable chemical atom or element. Each element can exist in several difference chemical reservoirs. Each element on earth moves among reservoirs in the solid earth, oceans, atmosphere, and organisms as part of geochemical cycles. Teaching standards: A, B, C, D, E, F Next Generation Science Standards HS-LS2-1: Use mathematical and/or computational representations of support explanations of factors that affect carrying capacity of ecosystems at different scales. HS-LS2-2: Use mathematical representations to support and revise explanations based on evidence about factors affecting biodiversity and populations in ecosystems of different scales. HS-LS2-3: Construct and revise an explanation based on evidence for the cycling of matter and flow of energy in aerobic and anaerobic conditions. HS-LS2-4: Use mathematical representations to support claims for the cycling of matter and flow of energy among organisms in an ecosystem. HS-LS2-5: Develop a model to illustrate the role of photosynthesis and cellular respiration in the cycling of carbon among the biosphere, atmosphere, hydrosphere, and geosphere. HS-LS2-6: Evaluate the claims, evidence, and reasoning that the complex interactions in ecosystems maintain relatively consistent numbers and types of organisms in stable conditions, but changing g conditions may result in a new ecosystem. Continued on the next page...

2 Next Generation Science Standards Continued... HS-LS2-7: Design, evaluate, and refine a solution for reducing the impacts of human activities on the environment and biodiversity. HS-LS2-8: Evaluate the evidence for the role of group behavior on individual and species chances to survive and reproduce. HS-ESS2-2: Analyze geoscience data to make the claim that one change to Earth s surface can create feedbacks that cause changes to other Earth systems. HS-ESS2-4: Use a model to describe how variations in the flow of energy into and out of Earth s systems result in changes in climate. HS-ESS2-5: Plan and conduct an investigation of the properties of water and its effects on Earth materials and surface processes. Common Core Standards ELA/Literacy RST : Assess the extent to which the reasoning and evidence in a text support the author s claim or a recommendation for solving a scientific or technical problem. RST : Cite specific textual evidence to support analysis of science and technical texts, attending to important distinctions the author makes and to any gaps or inconsistencies in the account. RST : Integrate and evaluate multiple sources of information presented in divers formats and media (e.g., quantitative data, video, multimedia) in order to address a question or solve a problem. RST : Evaluate the hypotheses, data, analysis, and conclusions in a science or technical text, verifying the data when possible and corroborating or challenging conclusions with other sources of information. WHST : Write informative/exploratory texts, including the narration of historical events, scientific procedures/experiments, or technical processes. WHST : Develop and strengthen writing as needed by planning, revising, editing, rewriting, or trying a new approach, focusing on addressing what is most significant for a specific purpose and audience. WHST : Conduct short as well as more sustained research projects to answer a question (including a self-generated question) or solve a problem; narrow or broaden the inquiry when appropriate; synthesize multiple sources on the subject, demonstrating understanding of the subject under investigation. Mathematics MP.2: Reason abstractly and quantitatively. MP.4: Model with mathematics. Curriculum Guide Continued... Continued on the next page...

3 Common Core Standards Continued... Curriculum Guide Continued... HSN-Q.A.1: Use units as a way to understand problems and to guide the solution of multi-step problems; choose and interpret units consistently in formulas; choose and interpret the scale and the origin in graphs and data displays. HSN-Q.A.2: Define appropriate quantities for the purpose of descriptive modeling. HSN-Q.A.3: Choose a level of accuracy appropriate to limitations on measurement when reporting quantities. HSS-IC.B.1: Evaluate reports based on data.

4 Thermohaline Circulation Lesson Plan Seabee divers from the Underwater Construction Teams work on a variety of projects in freshwater and seawaters, and sailors in the U.S. Navy navigate the ocean waters needs to understand thermohaline circulation. This circulation is important moving warm and cold water around the globe affecting the weather. Here are a few experiments to learn about water currents in the world s oceans and understanding fresh, salty, cold, and hot waters. Lesson Goal: Students will observe the effects of the layering of warm and cold water and the differences of water and their saline levels. Objectives: Learn about the difference in density of saltwater vs. freshwater. Discuss the implications of global climate change as it pertains to thermohaline circulation Grade Levels: 8th-12th Teacher Prep Time: 20 Minutes Lesson Time Needed: 80 Minutes Complexity: Intermediate DATA MANAGEMENT A worksheet is provided to allow students to document their experiments. What is Thermohaline Circulation, also known as the Great Ocean Conveyor Belt? (thermos = temperature, haline = salt) Thermohaline circulation is the part of the ocean circulation which is driven by density differences. Seawater density depends on temperature and salinity. Differences arise from heating and cooling at the sea surface and the introduction of freshwater into the salty sea water. Heat sources at the ocean bottom play a minor role. Translation: Thermohaline circulation moves a massive current of water around the globe. These currents slowly turn over water in the entire ocean like a giant conveyor belt, moving warm surfaces waters downward and forcing cold, nutrient rich waters upward. So, the ocean slowly turns over from top to bottom in a continuous global loop. The thermohaline circulation moves nutrients from one part of the ocean to another. In the seas near Norway and Greenland, the water is cold and sometimes freezes, leaving salt behind. The cold salty water becomes dense and sinks to the ocean floor. This water, known as the North Atlantic Deep Water, drives the water south towards Antarctica where the water flows east with the Antarctic Circumpolar Current, a powerful current that circles the continent. Parts of the Antarctic Circumpolar Current flow northward to the Indian and Pacific Oceans where the water warms up and rises, bringing up the nutrients to the surface. The water eventually travels back to the North Atlantic Deep Water to complete the loop; it takes approximately 1000 years to complete.

5 Introduction: Oceans make up 3/4 of the earth s surface and large-scale ocean circulation patterns help regulate global temperatures, shape weather and climate patterns, and cycle elements through the biosphere. Unlike the atmosphere, pressure changes at a linear rate. Atmospheric pressure at sea level is 14.7 pounds per square inch and pressure increase by an additional atmosphere for every 10 meters of descent under water. This is well known to scuba divers who have experienced painful ear squeeze from pressure differences between the air in their ears and the seawater around them. From the National Oceanic and Atmospheric Administration. National Weather Service.

6 Mixing is a key dynamic in the oceans, creating currents and exchanges between cold, deep waters, and warmer surface waters. This process redistribute heat from low to high latitudes, carries nutrients from deep waters to the surfaces, and shape the climates of coastal regions. One of these mixing process is from thermohaline circulation.

7 Thermohaline circulation is a key mechanism that helps regulate the earth s climate. This mixing is caused by differences in density between colder, saltier water and warmer, fresher water. Because the density of water increases as it becomes colder and saltier, it sinks at high latitudes (in the north Atlantic) and is replaced by warm water flowing northward from the tropics. The thermohaline circulation is often referred to as the global conveyor belt because it moves large volumes of water along a through the Atlantic, Pacific, and Indian oceans.

8 Concepts: Cold water is denser than warm water and will sink below the warmer water. Water that is more saline is also more dense than water with lower salinity and will sink below the water of lower salinity. Water temperature has more of effect on water movement than salinity. Thermohaline circulation is driven by buoyancy differences in the upper ocean that arise from temperature differences and salinity difference. Ocean temperatures are lower in the polar regions and higher at the equator because the equator received more radiant energy from the sun, making the waters warmer. In contrast, salinity differences are caused by evaporation, precipitation, freshwater runoff, and sea ice formation. When sea water evaporates or freezes, most of its salt content is left behind in the ocean, so hig rates of evaporation in the subtropics raise salinity levels. Sea water is relatively less saline at higher latitudes because these regions have more precipitation that evaporation. Melting sea ice returns fresh water into the oceans. When putting these two factors together, water cools in the North Atlantic and becomes dense enough to sink. Surface currents then carry the warm, salty water poleward to replace it. In the Indian and Pacific oceans, deep water returns to the surface thro ugh upwellings. Density is an important concept for students to understand. What appears to be minor changes with density differences caused by temperature and salinity may have a major impact in the oceans.

9 Experiment *Students should work in groups of two for best results in student comprehension. Materials Needed: At least 4 scales to measure salt A pound of table salt to share Ice to chill their solution Source of hot water or a heating plate to warm water Food dye in two colors (preferably red and blue) Each pair of students should have a clear plastic container (shoebox size, can hold at least 2 liters of fluid) Each pair of students should have one 1 liter and two 500ml beakers for mixing and pouring Each pair of students needs access to 4 liters of room temperature water Make sure that students follow instructions closely to have visible results. If solutions are not carefully combined, results maybe difficult to observe. Step 1. Making the Solutions: Mix 2 liters of saltwater solution and pour into the shoebox for the temperature test. A. Dissolve 35grams of NaCl (salt) into a liter of room-temperature water. B. This roughly represents the salinity of seawater at 3.5% Step 2. Temperature Test: Create 500ml of hot and 500 ml of cold seawater. A. Cold water can be made by chilling a beaker of the seawater in an ice bath for minutes. B. Warm seawater can be made by warming the solution on a hot plate or using hot tap water to make the solution. Once the solutions have reached their respected temperatures, add a few drops of food coloring into each. Preferably: red=hot and blue=cold. Step 3. Make a Hypothesis: What are your predictions about which layer will rise to the top? Record predictions and reasoning regarding hypothesis.

10 Experiments Continued... Step 4. Observe and Record: Gently pour the contents of each beaker into the opposite ends of the container. **Caution: Do not pour the solution too quickly or they will mix and not layer** Allow time for the solutions to settle. Observe the layering and make notations in their lab books. Discard the solutions in the drain and rinse the container for the next test. Step 5. Salinity Test: Mix 1 liters of saltwater solution and pour into the shoebox for the temperature test. A. Dissolve 35grams of NaCl (salt) into a liter of room-temperature water. Have half of your groups make seawater that is 1/4 as salty as normal seawater. A. Mix 8.75 grams of salt per liter. B. Color this solution blue. Have the other half of your groups make seawater 4 times as salty as normal: seawater. A. Mix 120 grams of salt in a liter of water. B. Color this solution red. Have students share half of their solutions with a group that has made the other solution. Step 6. Make a Hypothesis: What are your predictions about which layer will rise to the top? A. Hypertonic= greater or more than the solution B. Isotonic= same as the solution C. Hypotonic= under or less than the solution Record predictions and reasoning regarding hypothesis. Step 7. Observe and Record: Gently pour the contents of each beaker into the opposite ends of the container. **Caution: Do not pour the solution too quickly or they will mix and not layer** Allow time for the solutions to settle. Observe the layering and make notations in their lab books.

11 Discussion Where in the ocean water does the more salty than seawater exist and where does the less salty water than the regular seawater exist? Which is more important to the layering: temperature or salinity? Ask students to propose an experiment to determine which is more important A. Have students test the temperature solutions with solutions of different salinity and have them report their results on the lab sheet. B. Ask them how this impact their daily lives? Ex. Climate change with global warming.

12 Name: Date: Thermohaline Experiment Student Worksheet Hot and Cold Water Test: Hypothesis: Observation: (Describe your results in terms of the density of the solutions.) Salinity Water Test: Hypothesis: Observation: (Describe your results in terms of the density of the solutions.) How does salinity affect ocean layering? How does temperature affect ocean layering? Plan and execute a simple experiment that attempts to show which of the factors, temperature or salinity, has more of an impact on ocean layering. Which has greater impact on the oceans, salinity or temperature?