In this activity students will create and observe a model of the water cycle, including evaporation, condensation, and precipitation.

Transcription

1 (1 Hour) Addresses NGSS Level of Difficulty: 2 Grade Range: K-2 OVERVIEW In this activity students will create and observe a model of the water cycle, including evaporation, condensation, and precipitation. Topic: Water Cycle Real-World Science Topics: An exploration of clouds and the water cycle. Objective Students will be able to describe the water cycle by creating and observing a model. Materials Needed for Student Activity Materials Needed for the Warm-up Activity water sponge Materials Needed for Each Group of Students clear large bowl clear cup plastic wrap water mild heat source (window with sunlight, blow dryer, radiator in the classroom) Teacher Preparation Teachers may want to test the activity before the lesson to determine how long the evaporation and condensation process will take in your particular setting. 1

2 NGSS Three-Dimensions Science and Engineering Practices Disciplinary Core Ideas Crosscutting Concepts Obtaining, Evaluating, and Commnicating Information Obtain information from various texts, text features (e.g., headings, table of contents, glossaries, electronic menus, icons), and other media that will be useful in answering a scientific question. ESS2.C: The Roles of Water in Earth's Surface Processes Water is found in the ocean, rivers, lakes, and ponds. Water exists as solid ice and in liquid form. Patterns Patterns in the natural world can be observed. 2

3 STEPS FOR WATER CYCLE 1. Warm-up Activity: Take a sponge and ask a student to wet the sponge with water from the sink. Allow the students to feel the sponge and describe what they feel. Wipe the sponge on the chalk board (or other hard non-absorbent surface) so that students can see a wet streak. As the streak dries, prompt students, Where is the water going? Students may say the water is drying or disappearing. Explain that even though the water particles are too small for us to see, they are evaporating into the air, so that we can t see them on the board any more. Explain that as the water cycle continues, the water particles in the air come back together and we can see clouds. 2. Ask students to think about clouds and how they are formed. Display the large bowl and pour a cup of water in. Explain that they will create a model to trap the water particles from the bowl that would normally evaporate into the air just like the water from the chalk board did. Explain the model will represent the water cycle on Earth. If students do not have background knowledge on the water cycle, be sure to provide additional readings and images during this discussion. 3. Demonstrate the construction of the model. Place the cup inside the bottom of the bowl, pour water in the bowl around the cup (you may need to weigh the cup down), and cover the bowl with plastic wrap. 4. Distribute materials to each group of students and have them create the model. Have students record a diagram of their model and make predictions about what will happen to the water in the bowl on the Student Handout. 5. Have students observe and record observations daily as the water evaporates. (If you use a blow dryer or radiator, this process may be quickened and students will need to observe mode frequently.) Ideally, you will be able to have students observe and record when water has collected on the plastic wrap, as well as after it has rained into the cup. 6. Wrap-up Activity: Prompt students to observe their model after water has rained into the cup. Lead a discussion asking, Where did the water in the cup come from? How does our model show how the water cycle works on earth? How are clouds formed? Where does rain come from? What happens when lakes and rivers become polluted? Water Cycle Extension Activity Students can re-create the model using salt water to represent the ocean, soapy water to represent polluted bodies of water, or ice to represent snow. Students could also record cloud cover in the sky compared to rainfall collected in a measuring cup placed outside over an extended period of time. 3

4 BACKGROUND INFORMATION How do clouds form in nature? A great and very useful example of cloud formation occurs almost daily on hot summer days in the Rocky Mountains in the western United States. This forms due to what is known as orographic uplift, or when warm air blowing west to east rises as it passes over the mountains. As the warm, moist air rises, it cools rapidly and condenses around dust and other large particles in the atmosphere, forming large puffy cumulus clouds. What is the water cycle? The water cycle is the movement of water from the surface of earth, through the atmosphere, and back down to earth. Heat from the sun and earth warms a body of water or snow. The heat causes water molecules to evaporate into the air. The warm, moist air rises and cools as it ascends, condensing to form clouds. These water droplets remain suspended in the air until they become saturated and heavy. When this happens, the water droplets fall to earth as precipitation and the process repeats. 4

5 TEACHER HANDOUT Designing Our Water Cycle Model How did we build the water cycle model? Draw and label a picture to show. Students drawings should include labels of cup, bowl, water, plastic wrap, and heat source. Predictions What do you think will happen to the water in the bowl? Why do you think so? Students predictions are explained with evidence. Sample Answer: I think the water will evaporate and get stuck on the plastic wrap because the water from the sponge evaporated. Recording Results Draw and write to record your observations. Students drawings will vary but should show the water settled in the bowl, then collecting on the plastic wrap, and finally falling or collecting in the cup. Observations Observations: Observation # 1 Observation # 2 Observation # 3 Observation # 4 5

6 TEACHER HANDOUT Reflection Words to use: Water Rain Evaporate Condensation Cloud How does our model show how the water cycle works on earth? Sample Answer: Our model shows how water moves through the water cycle. The bowl can represent a lake. Water from the lake evaporates and collects in the sky. Our model shows this collection or condensation on the plastic wrap. When too much water collected on the plastic wrap, it rained down into our cup, just like when clouds collect too much rain, we have precipitation in the form of rain or snow. What do you think happens when lakes and rivers become polluted? Sample Answer: When lakes and rivers become polluted, I think some of the pollution gets into the air and rain as the water particles evaporate, condensate, and eventually precipitate back down. Think about the water cycle. How are clouds formed? Where does rain come from? Draw and label a picture to show. Student pictures should represent the water cycle including evaporation, condensation, and precipitation in a natural setting. Write about your picture: 6

7 STUDENT HANDOUT Name: Date: Designing Our Water Cycle Model How did we build the water cycle model? Draw and label a picture to show. Predictions What do you think will happen to the water in the bowl? Why do you think so? 7

8 STUDENT HANDOUT Recording Results Draw and describe your observations. Observations Observations: Observation # 1 Observation # 2 Observation # 3 Observation # 4 Reflection Words to use: Water Rain Evaporate Condensation Cloud How does our model show how the water cycle works on Earth? 8

9 STUDENT HANDOUT What do you think happens when lakes and rivers become polluted? Think about the water cycle. How are clouds formed? Where does rain come from? Draw and label a picture to show. Write about your picture: 9