Summer Science Lesson Plan: Water Pollution

Summer Science Lesson Plan: Water Pollution

Overview/Motivation: Kids will learn about the different causes of water pollution and ways they can help prevent it.Then they will get to make their own water purifier.

Materials

• Pictures of polluted waters and affected animals
• 2-liter soda bottle cut in half
• napkins or paper towels
• gravel, sand and cotton balls for the filter
• dirty water, you can make it by adding cooking oil, dirt, or small pieces of paper to water (we will also use food coloring)

Vocabulary

Pollution, environment, littering, water purification, sewage, sediment, fertilizer

Introduction

-Is there more land or water on Earth?71% of Earth is covered in water!

-How much of the water can we drink? 97.2% is salt water, 2.8% is fresh and a lot of this is trapped in glaciers—so what about what’s left? Can we drink all of that? No! Not only can we not drink it, but some of it is so dirty that we can’t swim in it and animals can’t live in it.

-40% of America's rivers are too polluted for fishing, swimming, or aquatic life.

-Even worse are America's lakes—46% are too polluted for fishing, swimming, or aquatic life

-Why is all this water so dirty? Can you name some causes of water pollution? Kids will come up with their own stuff here, but some causes you may want to elicit from them are:

-Plastic waste: Each yearit kills around 100,000 marine mammals,1 million sea birds, and countless fish worldwide (pictures of this would be good).

-Sewage: 850 billion gallons of raw sewage are sent into US rivers, lakes, and bays every year by leaking sewer systems and inadequate combined sewer/storm systems that overflow during heavy rains.

-Chemical and industrial processes: In the US, 34 billion liters per year (60%) of the most hazardous liquid waste—solvents, heavy metals, and radioactive materials—is injected directly into deep groundwater via thousands of "injection wells."

-Sediment: When forests are "clear cut," the root systems that previously held soil in place die and sediment is free to run off into nearby streams, rivers, and lakes.

-Pesticides: Pesticides that get applied to farm fields and roadsides—and homeowners' lawns—run off into local streams and rivers or drain down into groundwater, contaminating the fresh water that fish swim in and the water we humans drink.

-Fertilizers/Nutrient Pollution

-Oil, gasoline, and additives: big oil spills like the Exxon Valdez in Alaska cause serious pollution (11 million gallons—killed billions of fish and hundreds of thousands of animals), but when you add up all the little bits of pollution—like drips of oil, fuel, and fluid from cars and trucks; dribbles of gasoline spilled onto the ground at the filling station; and drips from industrial machinery—these sources and more combine to provide a continual feed of petroleum pollution to all of the world's waters, imparting an amount of oil to the oceans every year that is more than 5 times greater than the Valdez spill.

-Others: poorly designed landfills, CO2, rising global temperatures

Activity (groups of 2 or 3, but maybe more if it’s a huge class)

• Put the top half of the soda bottle upside-down (like a funnel) inside the bottom half. The top half will be where they build their filter; the bottom half will hold the filtered water.
• Layer the filter materials inside the top half of the bottle. Think about what each material might remove from the dirty water and in what order you should layer the materials. For an added challenge, use only two of materials to build your filter. Also, if kids are having trouble, give them a hint to put the cotton balls in first, then the sand, the another layer of cotton balls and sand/napkins.
• Pour the dirty water through the filter. What does the filtered water look like?
• Take the filter apart and look at the different layers. Can you tell what each material removed from the water?
• (Time permitting) Wipe the bottle clean and try again. Try putting materials in different layers or using different amounts of materials.

Discussion

-We just made a filter to clean our own dirty water. This is how basic water purification processes work. Mention Brita water filters—does anyone use them? It’s the same concept (can mention activated carbon to older kids).

-Ask the kids if they can use one filter forever. They will probably know that you need to change them, as they eventually get dirty and don’t work as well. To show this, put some water that has a light amount of food coloring in it through the filter. At first, the water will come out relatively clear. However, as time goes on, the water eventually will start to be colored. This is because the filter can only take out a certain amount of the food coloring.

-On a bigger scale, a variety of technical solutions are available to filter out chemical waste from industrial processes.

-Back to what we can do: ask class for ways they can help reduce water pollution: don’t litter, pick up litter, properly dispose of wastes so that they don’t leak into the ground and eventually make it into our water supply, etc

-There is a lot of pollution out there, but there are ways to fight it, just like we saw today—everyone has a role to play in reducing pollution!