Lesson Plan: Harvesting the Rain

Subjects:

Earth Science/Environmental Science; Social Studies, particularly Geography

Grade Level:

7-12

• Modifications for lower grades:
  • Lesson activities may be done as a class demonstration or in small groups
  • Consider running the simulation as a class prior to having students work on their own
• Modifications for higher grades:
  • Encourage students to make modifications to the simulation (starting population, per capita usage, runoff rate, etc.) to examine different possible situations (increased probability of drought, groundwater usage, etc.)

Lesson Duration:

2-3 class periods, depending on class length and grade level

Essential Questions:

• What makes a resource sustainable?
• How does water flow through the environment?
• Why is water scarce in some areas of the world?
• How do we model a water budget?
• How can rainwater harvesting affect water sustainability?

Lesson Objectives:

Students will:

• Examine human and climatic factors that influence the sustainability of water resources.
• Define water sustainability
• Describe the benefits of rainwater harvesting (decentralized, groundwater recharging, climate change mitigation)
• Explore visualizations to understand how the availability of fresh water resources is affected by natural variations in weather, changes in climate, and human activities that use water.
• Compare and contrast the rainwater harvesting methods used in India and the Southwest United States.
• Explain the difference between permeable and impermeable surfaces influence water availability
• Construct a physical model to simulate the effect of implementing rainwater harvesting on water sustainability

Materials:

• Retro Report video “Fighting Drought With an Ancient Practice: Harvesting the Rain” (Transcript)
• Student Activity handout
• Laptops/tablets for conducting research
• Lab Materials:
  • 1000 mL beaker, 25 mL graduated cylinder, disposable pipette (for Day 1 Step 3 demonstration)
  • Visualization: NASA Scientific Visualization Studio – A Map of fresh water
  • Aluminum drip pans (9”x13”) (2 per group; 16 for class of 30)
  • Small items to place between pans (marbles, clay, Lego bricks) (at least 4 per group)
  • Kitchen sponges (thin 5”x2.5”, cut in half) (8-12 per group)
  • 400 mL beakers (2 per group)
  • 100 mL graduated cylinder (1 per group)
  • Dice (1 per group)
  • Graduated cylinders, water
  • Simulation Instructions
  • Simulation Scorecard

Procedure:

Day 1 – Water Sustainability and Rainwater Harvesting

1. Activate prior knowledge about sustainability. Write the word sustainability in an area visible to students. Activate students’ prior knowledge about sustainability by asking, “What do you think and feel when you hear the word sustainability?” This can be done as a quick writing activity or a think-pair-share routine. Elicit students’ answers and organize them in a t-chart (“THINK”/”FEEL”). Look for the following themes:
   1. Think: Business practices/advertising, climate change, environmental impact, future, resources (food, energy, materials, etc.)
   2. Feel: Positive/negative, green, urgency, challenging, clean
2. Develop a consensus definition of water sustainability. Is water a sustainable resource? What do we mean when we say “water sustainability”?
   1. Pair students and have them come up with a definition of water sustainability.
   2. Then have pairs of students join together and combine their definitions.
   3. Continue this process until the entire class comes up with a consensus definition of water sustainability. Possible definition: “Water sustainability is using the same amount or less of the water available from the environment.”
3. Demonstrate the distribution of water on Earth. Discuss the amount of water that is found on Earth. While about 71 percent of Earth’s surface is covered in water, only 2.5 percent of water is fresh water, the water needed for life on land to survive. Of this fresh water, only about 1.2 percent is available as surface water. The rest is located in the ground (30.1 percent) or in glaciers and ice (68.7 percent)
   1. To learn more about the water on Earth, visit:
      1. The distribution of water on, in, and above the Earth | United States Geological Survey
      2. How Much Water is There on Earth? | United States Geological Survey
   2. To demonstrate this idea, fill a 1000 mL beaker (or 1 L container) with water. This represents the total amount of water on Earth.
   3. Pour out 25 mL of water into a graduated cylinder or small beaker. This represents the amount of fresh water. Use a dropper to take out 6 drops of water into a small cup or your hand. This represents the amount of fresh water available on Earth’s surface.
   4. Ask, “How does this demonstration change your perception of water as a resource on Earth?”
4. Discuss the factors affecting the availability of fresh water around the world. Explore the visualizations created by NASA scientists to understand how the availability of fresh water resources is affected by natural variations in weather, changes in climate, and human activities that use water.
   1. In the visualizations presented, blue represents increases in fresh water storage on land and red represents decreases.
   2. Look at the visualization at the top of the page (as a class or individually).
   3. Ask, “What patterns do you notice in the availability of fresh water around the world?”
   4. Students should write their answers on the Student Activity Handout.
      1. Note the locations featured in the documentary (Zimbabwe, India, Southwest US).
5. Watch the video explaining the visualizations individually or as a class.
   1. Answer the following:
      1. How was this data collected?
      2. Over what time period was this data collected?
   2. For each of the locations featured (Greenland, California, Okavango Delta in southern Africa, northern Saudi Arabia, northwestern China), describe the causes of the changes (increase or decrease) in fresh water storage.
6. Watch the Retro Report video “Fighting Drought With an Ancient Practice: Harvesting the Rain.”
   1. Introduce the documentary by pointing out regions featured in the documentary on a map or on the visualization discussed in Step 4.
   2. These are regions where fresh water is being depleted; however, people are rediscovering ancient practices to fight drought.
   3. As they watch the documentary, students answer the prompts on the accompanying Student Activity Handout. Pause the video as needed to allow students to answer questions.
7. Extension/Homework: Assign students to research United Nations Sustainable Development Goal 6: Ensure Access to Water And Sanitation for All.
   1. Based on their research, students develop an argument for the claim that rainwater harvesting can contribute to meeting targets related to this goal.
   2. Younger students may be assigned this infographic and/or short reading, along with a simplified reflection assignment.

Day 2 – Simulating the Impact of Rainwater Harvesting

8. Set up the model. If necessary, review the concept of a model in science (a physical, conceptual, or mathematical representation of a real phenomenon that is difficult to observe directly).
   8. Show how to set up the model with the following components:
      8. Aluminum trays: The model uses two aluminum trays, one on top to represent the land surface and one below to capture the runoff. The trays represent the surface area of land where people live. Carefully poke a small hole in the corner of the upper tray to represent a storm drain. In the lower tray, place small blocks (e.g. marbles, clay, Lego bricks) between the trays to create space between the lower and upper trays (see picture on left below). The corner diagonal from the hole should be slightly higher so that water will run toward the drain. Demonstrate what happens when water falls on this surface (i.e. flows from the high point to the low point). Take this opportunity to explain the difference between permeable and impermeable surfaces if students are unfamiliar with these terms.
      9. Sponges – Cut the sponges in half; place one half-sponge in the upper tray (see right picture below). Each sponge represents a rainwater harvesting method implementation (one for rain barrel, two for curb cut/basin). During a rain event, the sponges will soak up some of the rain, which can be harvested by squeezing the water out of the sponge into an empty beaker.

The lower tray (above left) has objects in corners to create space between trays and tilt the upper tray toward the drain. The upper tray (above right) is placed in the lower tray with a hole in the bottom right corner to represent storm drain. Sponge, beakers and graduated cylinders simulate rain and rainwater harvesting.

Beakers and Graduated Cylinder: Fill one beaker with water to represent rainwater. The graduated cylinder will be used to simulate rain by pouring a measured amount over the tray surface. To harvest rainwater, students squeeze out sponges into the empty beaker and pour into the empty graduated cylinder to measure the rainwater. If needed, empty the water collected in the lower tray to refill the beaker.

Student safety reminder: Handle aluminum pans carefully; check for sharp edges on pan before use; clean up any water spills immediately.

9. Explain the rules of the simulation.
   9. The goal of this simulation is to achieve water sustainability while supporting a growing population. This can be defined by having a positive water balance after 10 rounds. Recommended starting state: Population = 20, 1 sponge in the upper tray (placed anywhere), Water Balance = 20.
   10. Each round begins with rolling a die. Demonstrate what happens after rolling each number. Below are the rules for each number:

         Drought – record zero precipitation; no harvested rainwater and water balance will not change; subtract population from water balance

        Build – Community adds a rainwater barrel system; add 1 sponge to tray; roll again

        Rain – Roll again to determine the amount of precipitation (1=10 mL, 2=20 mL… 6=60 mL); record the event, then follow the directions for “rain event”

        Build – Community builds a curb cut and rainwater basin; add 2 sponges to tray; roll again

        Rain – Roll again to determine the amount of precipitation (1=10 mL, 2=20 mL… 6=60 mL); record the event, then follow the directions for “rain event”

        Population Growth– add 10 to population; roll again

   11. Note that rolling an odd number results in advancing forward one round; rolling an even number results in changing the model and rolling again (no round advancement).
   12. Note that a drought results in no precipitation and no rainwater harvesting. However, the water balance will still be used by the population. If the water balance is too low, this can result in a negative water balance.
   13. After rolling a Rain (3 or 5), students roll again to determine the amount of rain. Fill the graduated cylinder with the appropriate amount and record in the precipitation column. Harvest rainwater by squeezing out the sponges into an empty beaker. Record the amount of rainwater harvested and add to the water balance from the previous round.
   14. After a drought or rain, subtract the population value from the water storage to get the new water balance. Note that the balance may be negative if multiple droughts occur or the population growth outpaces the rain.
10. Students run the simulation. Distribute materials to groups of 2-4 students. Have students complete at least one complete simulation (10 rounds), filling out the Simulation Scorecard.
    9. If time permits, allow students to run the simulation multiple times.
11. Conduct a debrief. After collecting materials, ask students to discuss their experience with the simulation.
    9. Ask students to share whether they were able to achieve water sustainability through all 10 rounds and the factors that affected their ability to do so.
    10. Discuss how well the simulation represented natural (i.e. water cycle) and manmade (i.e. rainwater harvesting practices) systems.
    11. Have students answer the assessment/reflection questions in the Student Activity worksheet.

Extension Activities:

• Related lesson and activity: Rain Savers
• Retro Report Future of Water lesson and activity: The increasing scarcity of drinking water has captured the world’s attention and driven scientists and conservationists to find solutions. This 10-minute video and accompanying lesson has students examine how the country of Namibia has tapped an unlikely source of water to combat shortages and experiment with water filtration materials and strategies. Have students design and build a basin using the resources and lessons below:
  • Water Harvesting | Rainwater Harvesting for Drylands and Beyond
  • Water Education for Teachers and Students | The University of Arizona, Arizona Project WET
• Model a water budget for a watershed:
  • Modeling the Water Budget | Jet Propulsion Laboratory, California Institute of Technology

About the Author:

Jeremy Wang is the Director of Science Instruction at St. Thomas More Catholic School in St. Paul, Minn., where he also teaches middle school science. He earned his Ph.D. in Educational Psychology from the University of Minnesota, researching conceptual change in science education. He has experience in curriculum and assessment development at the College Board and University of Wisconsin.

Standards

Next Generation Science Standards

• MS-ESS2-4: Earth’s Systems: Develop a model to describe the cycling of water through Earth’s systems driven by energy from the sun and the force of gravity.
• MS-ESS2-1: Earth’s Systems: Develop a model to describe the cycling of Earth’s materials and the flow of energy that drives this process.
• MS-ETS1-4: Develop a model to generate data for iterative testing and modification of a proposed object, tool, or process such that an optimal design can be achieved.
• HS-ESS3-1: Construct an explanation based on evidence for how the availability of natural resources, occurrence of natural hazards, and changes in climate have influenced human activity.
• HS-ESS3-6: Earth and Human Activity: Use a computational representation to illustrate the relationships among Earth systems and how those relationships are being modified due to human activity.
• HS-ETS1-1: Analyze a major global challenge to specify qualitative and quantitative criteria and constraints for solutions that account for societal needs and wants.

AP Environmental Science

• STB-1: Humans can mitigate their impact on land and water resources through sustainable use.
• Topic 5.12: Introduction to Sustainability
  STB-1.A: Explain the concept of sustainability.
  STB-1.A.1: Sustainability refers to humans living on Earth and their use of resources without depletion of the resources for future generations. Environmental indicators that can guide humans to sustainability include biological diversity, food production, average global surface temperatures and CO2 concentrations, human population, and resource depletion.
  STB-1.A.2: Sustainable yield is the amount of a renewable resource that can be taken without reducing the available supply.
• Topic 5.13: Methods to Reduce Runoff
  STB-1.B: Describe methods for mitigating problems related to urban runoff.
  STB-1.B.1: Methods to increase water infiltration include replacing traditional pavement with permeable pavement, planting trees, increased use of public transportation, and building up, not out.

College, Career, and Civic Life (C3) Framework for Social Studies

• D2.Geo.3.6-8. Use paper based and electronic mapping and graphing techniques to represent and analyze spatial patterns of different environmental and cultural characteristics.
• D2.Geo.3.9-12. Use geographic data to analyze variations in the spatial patterns of cultural and environmental characteristics at multiple scales.
• D2.Geo.4.9-12. Analyze relationships and interactions within and between human and physical systems to explain reciprocal influences that occur among them.
• D2.Geo.10.6-8. Analyze the ways in which cultural and environmental characteristics vary among various regions of the world.
• D4.1.6-8. Construct arguments using claims and evidence from multiple sources, while acknowledging the strengths and limitations of the arguments.
• D4.4.6-8. Critique arguments for credibility.
• D4.4.9-12. Critique the use of claims and evidence in arguments for credibility.

Common Core Standards:

• CSS.ELA-LITERACY.RH.9-10.1: Cite specific textual evidence to support analysis of primary and secondary sources, attending to such features as the date and origin of the information.
• CCSS.ELA-LITERACY.RH.9-10.2: Determine the central ideas or information of a primary or secondary source; provide an accurate summary of how key events or ideas develop over the course of the text.
• CCSS.ELA-LITERACY.RH.9-10.7:I ntegrate quantitative or technical analysis (e.g., charts, research data) with qualitative analysis in print or digital text.
• CCSS.ELA-LITERACY.RH.11-12.1: Cite specific textual evidence to support analysis of primary and secondary sources, connecting insights gained from specific details to an understanding of the text as a whole.
• CCSS.ELA-LITERACY.RH.11-12.2: Determine the central ideas or information of a primary or secondary source; provide an accurate summary that makes clear the relationships among the key details and ideas.
• CCSS.ELA-LITERACY.RST.11-12.7: Integrate and evaluate multiple sources of information presented in diverse formats and media (e.g., quantitative data, video, multimedia) in order to address a question or solve a problem.
• CCSS.ELA-LITERACY.RST.11-12.9: Synthesize information from a range of sources (e.g., texts, experiments, simulations) into a coherent understanding of a process, phenomenon, or concept, resolving conflicting information when possible.