The Water Cycle (Sessions I and II)

Transcription

1 activities 18&19 The Water Cycle (Sessions I and II) BROWARD COUNTY ELEMENTARY SCIENCE BENCHMARK PLAN Grade 3 Quarter 2 Activities 18 & 19 SC.B The student knows that most things that emit light also emit heat. SC.D The student knows that the water cycle is influenced by temperature, pressure, and the topography of the land. SC.H The student knows that a successful method to explore the natural world is to observe and record, and then analyze and communicate the results. SC.H The student knows that to work collaboratively, all team members should be free to reach, explain, and justify their own individual conclusions. SC.H The student knows that to compare and contrast observations and results is an essential skill in science. SC.H The student knows that a model of something is different from the real thing but can be used to learn something about the real thing. SC.H The student knows that natural events are often predictable and logical. ACTIVITY ASSESSMENT OPPORTUNITIES The following suggestions are intended to help identify major concepts covered in the activity that may need extra reinforcement. The goal is to provide opportunities to assess student progress without creating the need for a separate, formal assessment session (or activity) for each of the 40 hands-on activities at this grade level. 1. Session I Activity 18: Ask, Why do we call this the water cycle? (Because a cycle means a circle. Water follows the path of a circle from liquid to gas, up into the air, where it cools and comes back down to Earth as liquid or frozen water.) Ask, What is the source of energy that makes the water cycle continue? (The sun provides heat energy.) What is the role heat plays in the water cycle? (It makes water evaporate into the air so it can then cool and condense into clouds and turn back to liquid water.) broward county hands-on science Quarter 2 169

2 2. Session II Activity 19: Tell students, The setup you used for this activity is called a model. The Water Cycle chart is also a type of model. Have students compare these two models. (They both show the same thing happening: water moving through the water cycle.) For each part of the Water Cycle chart model, have students identify that part as represented in the Water Cycle Chamber model. 3. Use the Activity Sheet(s) to assess student understanding of the major concepts in the activity. In addition to the above assessment suggestions, the questions in bold and tasks that students perform throughout the activity provide opportunities to identify areas that may require additional review before proceeding further with the activity. 170 activities 18 & 19 The Water Cycle

3 activities 18&19 The Water Cycle OBJECTIVES Students build water cycle chambers that show what happens to precipitation after it falls and compare their model with pictures of the water cycle in nature. As a class, they create a Water Cycle Chart. The students predict what happens to precipitation after it falls model the process by which water flows into lakes and oceans diagram the movement of water in a water cycle chamber compare their simulated water cycle with the water cycle in the environment create a Water Cycle Chart SCHEDULE Session I Activity 18 About 25 minutes Session II Activity 19 About 40 minutes, about 2 hours after Session I VOCABULARY water cycle MATERIALS For each student 1 Activity Sheet 18 1 pr safety goggles* For each team of two 1 stick clay, modeling 2 containers, plastic, 1-pt For the class 1 sht chart paper, approx. 1 m x 1.25 m* 2 crayons or markers, light blue* 1 pkg dots, blue, large 1 pkg dots, blue, medium 1 pkg dots, blue, small 64 ice cubes* 2 light sources 1 sht paper, construction, blue 1 sht paper, construction, brown 1 sht paper, construction, green 1 sht paper, construction, white 1 sht paper, construction, yellow paper towels* 1 set pictures, Water Cycle 2 pitchers* 1 spoon, plastic 1 roll tape, masking water, tap* Delta Science Reader Water Cycle *provided by the teacher PREPARATION Session I Activity 18 1 Make a copy of Activity Sheet 18 for each student Set up a distribution station with the masking tape, a pitcher of ice cubes, and a pitcher of water. Set up the light sources with paper towels on the table beneath them, as for Activity 16. Each team of two will need several paper towels, a stick of clay, two plastic containers, and access to the masking tape, water, and ice cubes. Session II Activity 19 1 Acquaint yourself with the descriptions on the backs of the Water Cycle pictures. broward county hands-on science Quarter 2 171

4 Display the pictures on a bulletin board where all the students can easily see them. Place the pictures in the order in which they are numbered. If you cannot get crushed ice, place several cubes in a plastic bag and hammer them into bits. Place the crushed ice and plastic spoon at a distribution station. Each team of two will need its water cycle chamber from Session I (Activity 18), several paper towels, and a spoonful of crushed ice. Tack the chart paper to a bulletin board or attach it to the board in preparation for the gradual construction of a display on the water cycle. Prepare the shapes of construction paper for use on the water cycle chart as follows: From the blue construction paper cut shapes to represent bodies of water on Earth. Cut the brown paper as shown in Figure From the green paper cut out a plant as shown in Figure Cut a circle out of the yellow paper to represent the sun. Cut the white paper into cloud-like shapes. If necessary, Session II can be scheduled for the day after Session I. Since about 75 percent of all precipitation falls onto the oceans, most water vapor enters the atmosphere through evaporation from the oceans. At any given time, about 1 percent of the total water supply of the world is in the atmosphere. Figure What the finished water cycle chart will look like. Activity Sheet 18 The Water Cycle In the outline of the container, draw your mountain with its riverbeds. Add water and snow. Use arrows to show what happens to the water and snow. Label your drawing. Use the words mountain, riverbed, snow, water, cloud, water vapor, evaporation, condensation, precipitation, melt, and flow. BACKGROUND INFORMATION Only about 25 percent of all precipitation actually falls onto land. Of this, about onethird runs directly off into lakes, rivers, and streams, or soaks through the soil and eventually enters these bodies of water. The remaining two-thirds evaporates into the air. Less than 1 percent of precipitation falls into rivers and lakes. Another small fraction of precipitation, about 6 percent, is taken up by plants and then given off into the atmosphere through transpiration. 172 activities 18 & 19 The Water Cycle evaporation water water vapor cloud water flows down riverbeds on mountain precipitation mountain condensation snow melts and flows

5 1 Guiding the Activity Session I Activity 18 Remind the students about the models that they built and observed in the previous activity. Ask, What was missing from those models? Land was missing. Students may also mention plants, rivers, and so forth. 2 Tell the students that in this activity they will build the same type of model, but they will add land. Ask, What is the purpose of building a model with land in it? Give each team of two students several paper towels, a stick of clay, and two plastic containers. Tell the students to mold the clay into a mountain. Explain that the mountain should be no more than about 7.5 cm (about 3 in.) high and should have a wide base and two or three grooves running down the sides. If students do not suggest it, tell them that with land in their models, they can observe what happens to precipitation when it falls on land. The students should keep the clay on the paper towels in order to protect the table tops. Instruct the students to place their mountain in one of the containers. Show the students the distribution station. Tell them to build the same type of water cycle chamber that they built in Activity 16 (see Figure 16-1, page 163). You may wish to review the steps in making the chambers. Remind the students to label their containers with their names. Instruct the students to add four ice cubes to the tops of their containers and place the containers on the paper towels under the light sources. 3 Ask the students, What will happen to the water in the containers? Ask, What do you predict will happen to the water droplets that fall on your mountain? Ask, What was the purpose of making grooves in the sides of the mountain? Tell students they will observe their water cycle chambers again later. The water will evaporate from the bottom container and water vapor will condense on the walls of the container and fall back into the bottom container. Accept all predictions. Some students may say that the droplets that fall on the mountain will slide down the sides back into the water. These represent riverbeds. The students should predict that some of the water that falls on the mountains will flow into the rivers and then down the sides of the mountain. broward county hands-on science Quarter 2 173

6 Guiding the Activity Figure A closed water cycle chamber with a mountain and riverbeds. 4 Session II Activity 19 Have the students observe their water cycle chambers. Have them tap on the top of the upper container to make more drops of water fall off, as they did in the previous activity. Ask, What happens to the water that falls on the mountain? Remind the students that, as in the previous activity, their setup is a model of what happens in nature. To review, ask, What part of nature does the lower container represent? Ask, What does the light source represent? Ask, What do the droplets that condensed on the top of the container represent? Ask, What does the ice on top of the containers represent? Ask, What do the falling water drops represent? 174 activities 18 & 19 The Water Cycle Students may see some drops fall on the mountain and may see them roll down toward the water. a body of water such as a lake or ocean the sun a cloud colder air high in the sky precipitation; raindrops

7 5 Guiding the Activity Ask the students, In what ways does this model differ from the one in the previous activity? It contains a mountain with riverbeds and streambeds. Invite volunteers to summarize what is happening to the water in the containers. Students should say that the water, aided by the heat from the light source, evaporates into the air in the containers; the water vapor condenses on the inside of the upper container; water droplets fall off the upper container, slide down the mountain in small rivers, and enter the body of water. 6 Ask the students, What do you think happens to rain that falls on mountains in nature? The students should say that it rolls or flows down the mountains and eventually enters the ocean. Point out to the students that water droplets flow down small streams that join small rivers and then bigger rivers before entering the ocean. Ask, Have you ever seen this happening? Allow students time to relate their experiences with streams and rivers. To reiterate, ask the students, How does rain water get from the tops of mountains to the oceans? It flows through streams and rivers. 7 Turn the students attention to the pictures of the various stages of the water cycle on the bulletin board. Have the students look at the pictures one at a time, in order. For each picture, ask, What forms of water do you see in this picture? Answers will vary depending on the picture. Students should use words such as water, water vapor, snow, clouds, and water droplets. 8 Ask, What is happening to the water in this picture? Give each student a copy of Activity Sheet 18. Tell students to read and follow the directions for drawing and labeling their water cycle chambers. Answers will vary depending on the picture. Encourage the students to use the words evaporation, condensation, transpiration, precipitation, freeze, melt, and flow to describe the stages in the water cycle that each picture represents. broward county hands-on science Quarter 2 175

8 9 10 Guiding the Activity Begin a water cycle chart. Glue the blue construction paper bodies of water to the chart paper. Ask the students, What does the blue paper represent? Glue the brown construction paper to the chart alongside the body of water. Ask, What does the brown paper represent? Explain to students that the soil contains water. Tell them they can represent water in the soil by shading the brown construction paper with a blue crayon or marker. Invite volunteers to come up to the chart and do this. Glue the green construction paper plant to the chart on top of the soil. Ask, What does the green paper represent? Explain to students that water is stored in plants. Invite a volunteer to use the blue crayon or marker to show the water in plants. Ask, What happens to water in lakes or oceans, in the soil, and in plants on a hot day? Explain that water evaporates and goes into the air in the form of water vapor. Tell students that the water vapor can be represented by small blue dots. Ask, Where should we put these dots on the chart? Refer to Figure 18-1, page 172, to see how to position each part of the water cycle chart. the water and ice on Earth soil on Earth the plants on Earth Students may suggest that it evaporates and goes into the air. over the blue water, the brown soil, and the green plants Invite volunteers to place the dots on the chart. With the marker, add arrows pointing up to show evaporation. Explain to students that evaporation happens more quickly when the water, soil, and plants are warmer. Ask, What do we need to add to the chart to show what warms everything? Glue the yellow sun on the chart, near the top. Tell students this will represent the sun. 176 activities 18 & 19 The Water Cycle the sun

9 11 Guiding the Activity Show students the medium blue dots. Tell them that these represent drops of water. Ask students, Where should we put these? Students should suggest putting them on the plant to represent dew that sometimes forms on cool mornings. Invite volunteers to come up and place the blue dots on the surface of the green plant. Using the marker, add arrows pointing downward onto the plant from the water vapor dots in the air. Ask, What do these arrows represent? condensation of water vapor on plants 12 Glue the white paper cloud shapes to the chart. Ask, What do these represent? clouds Then ask, In what form is water in the clouds? small water droplets and water vapor Ask, What will we use to represent the water vapor in the cloud? small blue dots Ask, What will we use to represent the water droplets? medium blue dots Invite volunteers to come up and place the small and medium blue dots on the white paper clouds. Add arrows pointing into the cloud. Ask, What do these arrows represent? condensation Ask, What should we show on the chart coming out from the cloud? precipitation 13 Tell students large blue dots will represent precipitation. Invite volunteers to come up and place the large blue dots below the clouds. With the marker, add arrows pointing out of the cloud. Ask, What do these arrows represent? With a black marker, draw some mountains on the soil. Ask, How does water move along the mountains? Add arrows to the chart to show the movement of water down mountains and into bodies of water. condensation and precipitation It flows down mountains and into streams, rivers, lakes, and oceans. broward county hands-on science Quarter 2 177

10 Guiding the Activity To summarize, ask, What does our chart now show? Point out each item on the chart. Have a different student say what each item represents. Write the word cycle on the board. Ask, What is a cycle? Ask, What would be a good title for our chart? Write the title Water Cycle Chart across the top of the diagram. Ask, How does our chart show a water cycle? Be sure students understand that the water cycle is a repeated pattern of water movement on, beneath, and above Earth s surface. As appropriate, read or review pages 8 12 of the Delta Science Reader Water Cycle. blue paper: bodies of water and ice brown paper: soil green paper: plants blue crayon on brown paper: water in the soil blue crayon on green paper: water in plants yellow circle: sun small blue dots: water vapor that evaporated from soil, plants, and bodies of water medium blue dots on plant: water that condensed out of the air white paper: clouds small and medium blue dots in the sky: condensation of water vapor large blue dots falling from cloud: precipitation. something that goes around and around in a circle, or a pattern that repeats itself Students may suggest Water Cycle Chart or something similar. 178 activities 18 & 19 The Water Cycle

11 R EINFORCEMENT Have the students repeat the activity, but this time place small amounts of powdered drink mix on the mountains. Ask the students to predict what the water in the ocean will look like later in the day. Have them notice that it becomes colored as the water droplets flow down the mountain and into the ocean. SCIENCE JOURNALS Have students place their completed activity sheets in their science journals. C LEANUP Have the students remove the tape from the containers and discard it. Have them dump out the water and remove the clay. Have them rewrap the clay in its plastic if you wish to use it again in other classroom activities. Otherwise, you may dispose of it. Have students dry the containers and spoon and put the picture set, masking tape, and containers in the kit. Return the light sources to their location over the terrariums. 179 broward county hands-on science Quarter 2 179

12 Connections Science Challenge Have students model what happens to snow that falls on top of mountains. Have students wipe the water off the top plastic container of the water cycle chamber. Tell them to remove the top container and slightly flatten the top of the mountain. Then have them place a spoonful of crushed ice on top of the flattened mountain and reseal the containers. Have students identify what the crushed ice represents and predict what will happen to it. (The ice represents snow on the mountain. The snow will melt and run down the mountain.) Let students observe what happens in the water cycle chamber. Science Extension (Safety Note: The following activity involves collecting and preserving snowflakes on glass slides. If your students are mature enough, let them handle the materials themselves. Otherwise, collect the flakes yourself and let students simply examine the slides.) On a snowy day, arrange several glass slides on a sheet of cardboard so the slides do not overlap. Put the cardboard, slides, and a spray can of clear enamel in a covered box outdoors or in another protected place where the temperature is below freezing. When the slides and can are cold, spray the slides with a thin coating of enamel, then immediately expose the cardboard to the falling snow. When a few flakes have collected on each slide, put the cardboard in the cold, protected place again. Once the enamel is thoroughly dry, the flakes will be preserved. Let students examine them with a magnifier or microscope. 180 activities 18 & 19 The Water Cycle Science and the Arts As an extension of Science and Language Arts below, suggest that students write and perform a play about the water cycle using some of the ideas in their short stories. This could be done as a cooperative learning activity, with one group writing the script, another group serving as actors, a third group creating props and costumes, another recording and playing sound effects and music, and so forth. Encourage the scriptwriters to include several water drops traveling different routes through the cycle one drop evaporating from a puddle, another leaving a plant through transpiration, and the like. When the play is finalized and well rehearsed, let students present it on Parents Night or at a school science fair. Science and Language Arts Ask students to imagine that they are a tiny drop of water in an ocean, lake, pond, or puddle. Tell them to imagine all the changes they would go through and all the places they could go as they traveled through the complete water cycle. Have each student write or tape-record a short story based on these imaginary experiences. Science and Social Studies Suggest that students find and examine photographs of the Grand Canyon, and help them locate it on a United States map. Ask any students who have visited the Grand Canyon to describe what they saw. If students do not mention the river (the Colorado) flowing through the bottom of the canyon, prompt them to do so. Explain that the Grand Canyon, now about 1.6 km (1 mi) deep, was formed by the river as it wore away dirt and rock bit by bit over millions of years. 180