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Lesson: Water Quality and Turbidity

Lesson: Water Quality and Turbidity
Rick Riley | Mezzacello The view of the fish from within the pond.

This is a fun lesson: Water Quality and Turbidity. It uses a simple waterproof camera, iphone, android phone, or waterproof endoscope to see the world beneath the surface of the pond. Students are asked to make hypotheses on water health and oxygenation based on modeled parameters.

Important topics to cover are turbidity and nitrate-nitrite balances, oxygenation, and balanced ecologies. Students will not only observe the environment directly, they will also collect samples ain a controlled study. Then using the scientific method they will determine the health of the water.

Materials

  • Pond (preferably with fish)
  • A camera (see notes)
  • PH and pond testing strips
  • At least four sterile lidded clear control bottles
  • A powerful source of light
  • A plastic pipette
  • White tissue paper
  • A Turbidity graph
  • A string with a weight – or a measuring tape with a weight
  • A way of getting accurate measures like a measuring tape
  • A notebook
  • Pens and Pencils
  • Labels for the bottles and collected samples

Instructions

  1. Bring students to the pond. Ask them to observe three to five elements of the pond’s ecosystem.
  2. Record those observations in a notebook.
  3. Place into the pond a device for seeing underwater (preferably video) connected to a rod or secured by a string and record short bursts of video from three locations in the pond that are accessible.
    1. Test this apparatus in a sink or tub first!
    2. Losing your phone in a pond is NO BUENO!
    3. A dedicated $30 endoscope is a good choice. It does not give as much dramatic detail as a phone, but is much safer.
    4. Be advised USB endoscopes like this REQUIRE a USB enabled computer, so plan accordingly.
    5. In my experience being able to see the conditions in a pond IN the water really activates students as scientists. It is NOT a requirement, but it will deepen the sense of wonder and excitement for the students.
  4. Record the location of measurement and the depth of the body of water at that measurement.
  5. Collect a sample of water from each site observation in a water container with a lid.
  6. Take measurements of the pond with the PH pond testing strips.
  7. Return to a lab. Observe rested samples of water, Do students observe clear water or is there floating material?
  8. Using the turbidity chart, ask students to identify turbidity at each location.
  9. Graph turbidity conditions, depth, temperature, and PH on a chart.
  10. Using a plastic pipette ask students to carefully pull samples of water from the labeled bottles.
  11. Empty pipette onto white tissue paper and label the droppings.
  12. Allow the droppings to dry and ask students to observe the tissue drops through a strong light.
  13. Ask them what they see. Then ask them to explain their findings based on their collected data.
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