Clearwater: Hudson River Rising
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Title: Water Pollution

Despite decades of awareness, preservation, and clean-up efforts, water pollution is still a major environmental concern, both in the United States and around the world. In this lesson, students will learn about water pollution through various activities. They will see firsthand that not all pollution is visible; they will create their own polluted river and understand that pollution is harmful to animals, and they will learn about things that can be done to prevent pollution or clean already-polluted bodies of water.

Grade level: 3-4

Subjects covered: Science

Students will be able to:
  • describe some of the causes and effects of water pollution;
  • describe how water pollution is harmful to animals;
  • explain how they can help reduce water pollution.
Time Allotment: 3-4 class periods


For the Class:
3 clear plastic cups
3 spoons
white sugar (1/2 teaspoon)
salt (1/2 teaspoon)
vinegar (1 tablespoon)
water (1 liter)
a household sponge cut into the shape of a fish
soil (1 tablespoon)
brown sugar (1 teaspoon)
syrup (1 teaspoon)
paper dots (1 tablespoon)
soapy water (2 tablespoons)
red food coloring (5 drops)
green food coloring (5 drops)

Standards from the Mid-continent Research for Education and Learning: Science Standard 6, Level II

3. Knows that an organism's patterns of behavior are related to the nature of that organism's environment (e.g., kinds and numbers of other organisms present, availability of food and resources, physical characteristics of the environment).

4. Knows that changes in the environment can have different effects on different organisms (e.g., some organisms move in, others move out; some organisms survive and reproduce, others die).

5. Knows that all organisms (including humans) cause changes in their environments, and these changes can be beneficial or detrimental.

Prep for Teachers:
Cut one household sponge into the shape of a fish
Print the Freddy the Fish activity, available online at

Introductory Activity:

1. Before class, fill the three plastic cups with water.

2. Show the cups of water to your students and ask them what they see. Ask them what they think the cups contain and then tell them each cup has plain water.

3. Add salt to one cup of water, sugar to the second cup, and vinegar to the third cup, telling your students what each item is as you add it. Stir each cup with a separate spoon until the additives are dissolved.

4. Again, ask your students what they see. Does the water in each cup look the same? Does the water look clean? Does it look clean enough to drink? Which substance dissolved the easiest? Which substance, if any, did not dissolve completely?

5. Tell your students that just because they can't see something, doesn't mean it isn't there. The same is true for pollution.

6. Show students the following clip from 'Til the River Runs Clear. Tell them that while they view the clip, they should look for at least one man-made cause of pollution in the Hudson River.

7. After viewing the clip, ask your students what man-made pollution impacted the Hudson River. Tell the class that they will be learning about some other ways in which pollution enters bodies of water.

Learning Activity:

1. Print the instructions for the Freddy the Fish activity, available online at

2. Set the jar of clear water on a desk or table where all of your students can see it.

3. Hold up the sponge fish, and "introduce" Freddy to your class before placing him in the jar of water.

4. Follow the instructions for the Freddy the Fish activity. You can have your students read the story, or you can read the story and ask for volunteers to add each ingredient to Freddy's jar.

5. After you have finished reading the story and adding the ingredients to Freddy's home, ask your students to describe what they see. Retrieve the sponge fish from the jar to demonstrate to your students that pollution changes both the water and the animals that live in it.

Culminating Activity

1. Direct your students to the following Web site to learn about the ways in which humans pollute the water around them and what they can do to help keep our water resources clean. Allow them 5-10 minutes to explore the interactivity before they report their findings to you and their classmates. Ask them to explain how we pollute water and what we can do to prevent water pollution.

2. Afterward, tell your students that they are going to write a letter. For this activity, they will pretend to be Freddy the Fish writing a letter to someone who lives near his riverbank. In the letter, Freddy will describe the pollution in his home, and tell his human neighbor what s/he can do to help make Freddy's river a cleaner, healthier place.

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