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Settling Jar – Water Quality

Name of Corresponding Unit Plan: Human Impact on Lake Champlain

Grade Level: 4-12

Common Core Standards
RS.3. Follow precisely a complex multistep procedure when carrying out experiments.

RH/S.7. Conduct short as well as more sustained research projects to answer a question or solve a problem.

Content Areas: Science

Recommended Length/Duration: Initially 15-30 minute lesson, 5-10 minute daily observations, 15-30 minute summary of findings.

Learning Goals: Students will observe the changes in water quality over time. Students will understand the factors that affect settlement of particulates.

Description/Sequence:

  1. Introduce students to the task by discussing the way water looks after a heavy rain (muddy). Guiding questions might include:
    • What color is the water?
    • What gives the water that color?
    • Where does the material in the water come from?
    • What is the particulate in the water made of?
    • What happens to it?
    • How long does it take for the water to be clear again?
  2. Introduce the terms "particulate" and "suspension." Particles from the soil are suspended in the water during run-off.
  3. Explain that the class will be doing an experiment to observe how particulates that make up run-off settle to the bottom of a body of water.
  4. Take a large jar and place several scoops of earth into the bottom. Be sure your soil sample includes rocks, soil, and organic matter typical of local soils.
  5. Add water to about one inch from the top of the jar put on its lid.
  6. Ask students to describe what the soil sample and water look like. After soliciting ideas orally, have them record their observation on the first line of their observation worksheet. Guiding questions might include:
    • What is on the bottom of the jar?
    • What does the water look like?
    • Is anything floating on the surface?
  7. Shake the jar so that all the material is suspended in the water and then set it down in a safe place. Explain that the jar is not to be disturbed, only observed.
  8. Ask students to describe what the soil sample looks like now. After soliciting ideas orally, have them record their observation on the second line of their worksheet.
  9. Explain that students will make one observation each day until all the particulate has settled to the bottom. Leave the jar in the same place and enable students to make and record a daily observation.
  10. When all the particulate has settled to the bottom of the jar, ask students to share some of their observations. Guiding questions might include:
    • How long did it take for the particulate to settle?
    • What settled first? Last? Never?
    • How is the sediment on the bottom of the jar different than the soil sample that went into the jar?
  11. Discuss how run-off in a natural setting would affect water quality. Some guiding questions might include:
    • What would increase or reduce run-off in an actual location in the watershed?
    • What benefits and harm are the result of run-off?
    • How have students observed this in actual lakes and streams?

Assessments: Collect worksheets and evaluate for completeness, accuracy, and effort.

Materials/Resources: Large, clear class jars with lids, Soil samples, Settling Jar worksheet (pdf)

Special Considerations: Students with limited writing skills may need a recorder for their observations or could be teamed with a more able partner. This activity may take 2-14 days depending upon the composition of your soil sample. Extend the observation worksheet as needed.

Extensions: Students may want to try different soil samples, gravel, sand, silt, clay. Students may want to observe a local stream or lake to see how run-off affects its appearance.