Before class, add soil, oil, and/or food coloring to two of the three bottles of water. You should have one bottle with clear water, one should be very murky and muddy, and one should be in-between.
For the Model Wetland demonstration, gather materials ahead of time and prepare the model wetland (S-7-5-3_Model Wetland.docx). Make the wetland by adding modeling clay to the shallow pan, to represent land covering half of the pan sloping toward the bottom of the pan. Add enough water to the other half of the pan to cover the bottom, to represent a body of water such as a lake.
Show the class the three water bottles. Ask, “Which one would you like to drink? …swim in? Which one do you think a fish would like to live in?” Tell them that the clear one represents water in Pennsylvania before the colonists arrived, the dirtiest one represents the time in history when Pennsylvania’s water was the most polluted, and the other one shows water today, after some efforts have been made to clean up the water.
Tell students that the Pennsylvania Department of Environmental Protection (DEP) has been studying water quality and experts have found that at least 13% of Pennsylvania’s streams and lakes are polluted. Some of them are too polluted even to support communities of organisms. Say, “This lesson is going to focus on water pollution in Pennsylvania. But before we can understand the effects of pollution, we must learn about what healthy ecosystems need.”
Explain that organisms have very specific needs for their habitat in order to survive. Aquatic organisms are found where their needs for survival are met, and pollution can make whole communities of organisms unhealthy. Give students about 2–3 minutes to independently brainstorm the requirements for life of fish and other aquatic organisms. In other words, “What biotic and abiotic factors do fish need to survive?” Use students’ answers to make a list on the board and have students write the answers in their notes. The list can include: the right temperature, food, shelter, pH, and dissolved oxygen. (Note: You may have to provide the last two factors and explain them. See The Basics of Water Pollution in Pennsylvania Web site under Related Resources for more information.)
Ask students if they can name sources of pollution in Pennsylvania’s water. Accept reasonable responses, and then show them the Sources of Pollution Concept Map (S-7-5-3_Sources of Pollution Concept Map.docx). Add other sources of pollution that students have identified to the concept map. Explain how each source of pollution can affect fish and other aquatic organisms. See The Basics of Water Pollution in Pennsylvania Web site for background information (see Related Resources).
Demonstration: Model Wetland
Tell students that wetlands are areas of land that are covered with water for all or part of the year, and that they are found between dry land and bodies of water such as streams, lakes, and rivers. Wetlands prevent flooding and keep pollution out of the water. This activity will demonstrate how wetlands keep our water clean. Follow the procedure for the Model Wetland demonstration (S-7-5-3_Model Wetland.docx).
After your demonstration, have students write a paragraph explaining why wetlands are important for the organisms in aquatic ecosystems and also for people. If time is limited, this can be a homework assignment.
Local Human Effects on Ecosystems
Divide students into five groups. Give each group one of the photos of human effects on ecosystems (S-7-5-3_Human Effects.docx). Have the groups discuss what they see in the photo and answer the three questions below it. Allow about 10 minutes, and then have each group share responses to the photos. Have the whole class rank the human activities in the order of how much impact they have on aquatic ecosystems.
As a class, make a list to answer the question, “What can you do to help?” (Answers may include: educate yourself and others; look at what pesticides or fertilizers you use in your own yard; volunteer to help clean up.)
Public Service Announcement Activity
Have small groups of students create a public service announcement (PSA), in the form of a radio or television commercial, with the message that what you do on land affects water quality. The PSA should describe how human actions can affect aquatic ecosystems, and what we can do to help. If time permits, have students present their PSAs to the class.
- For students who need additional practice, reinforce concepts by guiding them in making a cause/effect chart for the types of pollution in the concept map. For each type of pollution, have them explain how it can change water quality and affect organisms. Also, explain how to make a public service announcement and provide an example, such as the one at: http://en.wikipedia.org/wiki/Public_service_announcement. Help students organize and plan for the PSA before they write it, and allow ample time for practice of the presentation.
- For students who might be going beyond the standards, assign one of the following reading selections in place of creating the PSA:
- Read “The Story of Honey Hollow” (see Related Resources) and create a timeline or episodic organizer to trace the history of human effects on the Honey Hollow watershed.
- Read the newspaper article “Some Allegheny County Streams, Rivers, Still Far from Meeting Pollution Standards: Don’t Go near the Water” and write a summary of it (see Related Resources at the end of this lesson). Students can present it to the class when they are presenting the PSAs.