Adapted from Animal Tracks Activity Guide, A Conservation Education Program, co-published by the National Wildlife Federation and National Education Association. This activity appeared in Sprinkles, the official water education newsletter of The Groundwater Foundation.


SUBJECTS:

Science, Social Studies, Geography, Health


PROCESS SKILLS:

Reading and following directions, observing results, hands-on manipulation, problem solving, developing vocabulary

Grades: 4-6

Time for Activity: 30-40 minutes

Key Vocabulary: Aerate, aquifer, bacteria, coagulation, chlorinate, filtration, micro-organism, reservoir, sedimentation

Intended learning outcomes:

Completing this activity will allow students to:

* Explain the steps and processes involved in purifying water at a water treatment plant
* Understand why water must be cleansed and purified before it is safe to drink
* Discover where the sources of drinking water occur in the area
* Recognize a career option that connects environmental and health issues


BACKGROUND:

When water falls to earth and flows into reservoirs, aquifers, and lakes, it collects direct particles, bacteria or pollutants. These contaminants must be removed before our water is sage to drink.

This activity simulates the treatment process water goes through before it flows from our tap. The United States has one of the best and leanest drinking water systems in the world.

Water is first aerated, by spraying it into the air to release trapped gasses and to absorb oxygen.

Next, powdered alum is added to the water. This binds to dirt particles suspended in the water (coagulation).

The particles, now called, "floc," become heavy and sink to the bottom (sedimentation). The water is then filtered through layers of sand, gravel, and charcoal to remove the small particles.

Finally, a small amount of chlorine is added to kill bacteria and micro-organisms.


MATERIALS:

1 pound bag of clean aquarium gravel
1 pound bag of clean sand
1 container of powdered alum (found in the spice section of a grocery store)
2 clear plastic cups per team
1 polystyrene (Styrofoam) cup per team of students
Paper towel cut in quarters
Eyedropper filled with non-chlorine bleach mixed with water (to stimulate chlorine)
Large bucket of water with 1 cup of dirt mixed into it
Large soup ladle (optional)
Handout


PROCEDURE:

* This activity works well with a discussion about aquifers and reservoirs. Ask students if they know the source of their local drinking water. Learn the name of the local reservoir or aquifer, and identify if on a map. Explain that they will learn how to properly treat water before it is released for consumption. Briefly explain how water is treated before starting this activity.

* Break the class into groups of 2-3 students. Provide instructions and ask students to consider the bucket of dirty water to be the reservoir. Instruct one student from each group to stir the water well with the soup ladle and use it to fill one clear plastic cup three-quarters full. Have the other students in the group collect the materials they need and set-up to simulation activity.

* Have the students follow the instructions. Offer assistance and supervise the activity as the students carry out their simulation.


THE WATER TREATMENT PLANT

Instructions


* Take one clear plastic cup to the "reservoir" and fill it three-quarters full of water.

* Using a pencil, punch eight to ten holes in the bottom of the white foam cup. Place a piece of paper towel of filter paper on the bottom of the cup. Put one inch of gravel in the cup. Cover the gravel with one inch of sand. Set this filter cup aside.

* Pour the dirty water in the clear cup. Repeat two more times. This step is called aeration.

* Take 1/2 tsp. alum and put it into the cup with water. The alum will bind to the dirt. This is called coagulation. The alum and dirt are heavy and will form a layer on the bottom of the cup. This is called sedimentation.

* Place an empty cup underneath the white foam cup with the sand and gravel filter. After the particles in the clear cup have fallen to the bottom, pour the water into the white foam cup. This step is called filtration. The water is coming through the filter is free of dirt.

* Place two drops of non-chlorine bleach into the clean water. If this were really chlorine, it would kill bacteria and micro-organisms in the water. If this were a real water treatment plant, you would now have water clean enough to drink.

* When cleaning up, save the water to water plants. Wash the clear plastic cups so they can be used again.


EXTENSIONS/MODIFICATIONS

Read The Magic School Bus at the Waterworks by Joanna Cole, or assign the book as homework reading. It reinforces the concepts presented here.

Take your students to a real water treatment or wastewater treatment plant.


Links
Groundwater Foundation Kids Corner
National Wildlife Federation Kids and Families