Freshwater Pollution Testing
Lesson 6 of 9
Objective: SWBAT determine if pond water is polluted, types of pollutants found, and levels of these pollutants.
What are some sources of saltwater?
I give students 2 minutes to write or draw answers to the question in their Science Journal. I also encourage them to write questions they may have. A Science Journal (Notebook) provides space for them to process their thoughts. I give them 1 minute to share with their partner and then 1 minute to share with the class as they Think Pair Share. The answer I am looking for include: oceans and seas.
What are some sources of freshwater?
Follow it up by creating a class list of sources of freshwater. Some answers I am looking for include: lakes, rivers, ponds, streams, marshes, bogs, groundwater, glaciers, and icecaps.
Teacher Tip: When student use their science journal it provides a means for them to develop their ability to express ideas in writing. Sometimes students write short answers, draw pictures, or write other questions they may have. Drawing is an important science skill because: pictures give support to the text, students like to draw and as they draw they develop a visual memory, and drawing compliments writing. Science journals, also called science notebooks, are a great tool for students to record their thoughts and reflect on them at a later date.
Freshwater Pollution Test
In this problem based learning (PBL) experience, students are exposed to outdoor environmental lessons. This outdoor learning experience enhances science, math, social studies, and language arts lessons. It is an interdisciplinary unit. This lesson ties together the Cross Cutting Concept (Cause and Effect) along with Science and Engineering Practice #4 (Analyzing and Interpreting Data).
Students test pond water and then after analyzing the collected data look for patterns and relationships between the water and human activities that directly or indirectly cause pollution. As students develop ideas and theories from the data, they will make connections to the causes of pollution and the effects of that pollution on the pond ecosystem.
Research has shown that learning in the context of the natural environment raises student achievement and this PBL Unit is an opportunity for students to practice informal science based inquiry. After spending time outdoors at a local pond, students bring back a sample of the pond water. Testing the pond water is a valuable experiment to understand the health of the ecosystem. Using the Lab Freshwater Pollution Testing, I give students background information about water and pollutants and identify key terms students should focus on such as: groundwater, pollutants, organisms, and ecosystem. The goal is to develop content vocabulary and we have a rich, real world context to do that in.
The lab leads students through the testing steps. Depending on where your students are at, you may want to review these steps prior to beginning the lab. At this point, I'm moving my students away from being dependent on me to "do their thinking" by having them review the lab within their lab groupings. I spend that time cruising and listening in, and try to avoid answering students' questions about the procedure. I do this by restating the question they're asking me (and perhaps tightening up the thinking a bit), or by restating it exactly as I've heard it and following up with questions such as, "Tell me more about....", and "How do you know...". Of course, a great question to ask is, "Can you find the answer in the directions?"
In the lab, students perform three Freshwater Pollution Tests (dissolved oxygen, chlorine, and pH) because these tests are common indicators of pollution. From these indicators, students will understand how people commonly affect our waterways. They should also come away with an understanding of nonpoint source pollutants, which are pollutants that do not come from a specific location.
As students perform these tests, they will assess the health of the ecosystem at the pond and by analyzing the data collected will begin to form their argument to the essential question "What are the benefits of parks in a community?"
The purpose of this entire learning experience is to spark my students to apply what they've learned from gathering their scientific data. I ask them to respond to these real world questions:
What can be done to help minimize the amount of pollutants in our local sources of water? Give examples. Answers will vary depending on the results of your tests but could include: stop or control the amount fertilizers used on the grass in the area, clean up the parking lot which has residue from cars such as leaking oil and rubber from tires.
Would you describe our water at the pond as polluted on non-polluted? Defend your answer. Answers will vary depending on the results of your tests but could include: yes the water is polluted if the amount of dissolved oxygen is low, yes the water is polluted if the chlorine is high, yes the water is polluted if the pH is above 9 or below 6.
It is important to take time to analyze the results with the class so that all students will have an understanding of the levels of pollution. As students analyze the data collected from the Freshwater Pollution Tests, they begin to piece together the foundation for their argument to the essential question, "What are the benefits of parks in a community?"