Lab 8: Drought Mitigation Trade-offs

The lab activity described here was created by Betsy Youngman of Phoenix Country Day School and LuAnn Dahlman and Sarah Hill of TERC for the EarthLabs project.

Context for Use

This is a culminating experience for a unit on drought. Lab 8 turns the responsibility for background research, modeling, and evaluation over to student teams. The lab has students working in small groups and using common lab equipment.

Estimated Time Required:

• 1 class period to read and research
• 1 class period for hands-on activity
• 1 class period to prepare and practice presentation
• 1 class period to share presentations with class

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Activity Overview and Teaching Materials

This lab assigns students to work in cooperative research teams of 3 - 6 students. Student teams are assigned to one of the following mitigation strategies and asked to present a report to the class.

Dams and Reservoirs

Students investigate the costs and benefits of building dams and reservoirs to mitigate drought. They use their physical model from Lab 2 to conduct a simple investigation to model dams.

Materials needed for hands-on activity

• watershed models from Lab 2
• clay

Cloud Seeding

Students investigate the costs and benefits of cloud seeding to mitigate drought. As a illustration of the strategy, they create clouds in a bottle to demonstrate the role of small particles in cloud formation.

Materials needed for hands-on activity

• clear plastic bottle with pop-up cap
• matches
• water

New Farming Technologies

Students investigate the costs and benefits of new farming technologies to mitigate drought. Students build a simple model to illustrate the strategy of drip irrigation.

Materials needed for hands-on activity

• 1- or 2-liter plastic drink or water bottle with a flat-surfaced cap
• hammer and a small finishing nail OR a hand drill with small drill bit
• serrated knife or tin snips to cut plastic bottle
• potted plant with in a 6-inch or larger diameter pot
• water

Desalinization

Students investigate the costs and benefits of desalinization to mitigate drought. Students set up a simple distillation demonstration to show the energy it takes to remove salt from water.

Materials needed for hands-on activity

• 400 mL beaker with 200 mL tap water plus 7 g salt
• hot plate
• ring stand
• glass funnel
• clamp
• one-hole stopper with bent glass tube
• rubber tubing
• 200 mL beaker
• watch glass

Printable Materials

This lab does not have any Stop and Think questions. You will need to assess student learning based on their contributions to the small group work and the product they produce to communicate their findings.

Teaching Notes and Tips

At this point in the unit students are well versed in drought terminology and the techniques for conducting simple investigations. For this activity students are grouped into small expert teams. There are 4 types of mitigation strategies to investigate so teachers should assign one small group of 3 - 6 students to each strategy. If need be, more than one group can investigate a single strategy. This activity uses a jigsaw mode of teaching strategies, separating your class into subgroups who will then report back to the full class. To learn more about cooperative strategies, visit the Cooperative Learning page on the Starting Point website.

Assemble all materials for the hands-on activities ahead of time. To supervise these diverse activities, designate one class period as the hands-on lab period. Students can conduct their activities and prepare the apparatus so they can share a demonstration of it during the presentation day. You will need to be moving around the room ensuring that all students are working safely.

For the background research you may decide it is best to print out selected articles for the teams to read and review in class.

Students will need to work cooperatively in preparing their presentation to share with the class. One technique to encourage sharing of responsibility is to create a template slide for students to use in PowerPoint or some other presentation method. Giving them the headings such as introduction, positive benefits, costs, negative impacts on the environment, etc., will help the groups stay on task.

Assessment

Students should be assessed on their individual contributions to their group's successful project.

State and National Science Teaching Standards

Additional Resources

This article from Yale Environment 360 is included as an extra resource in Lab 8C - Can Cloud Seeding Help Quench the Thirst of the U.S. West?.

Pedagogic Considerations

If you are unfamiliar with having students working in groups, take a look at the Starting Point website on Cooperative Learning.