Try This

Take the Filter Challenge

Objective
To work as a team and build the most efficient water filtration device using the items given. Background Have you ever wondered how a municipal water treatment plant is designed? It is an intricate and tedious process that has gone through many years of work to create the modern water treatment processes we see today.

Duration
30 minutes

Age Range
5th grade through adult

Materials
Filter Materials (you will need one set of filter materials for each team)

• 2 cups of gravel
• 2 cups of sand
• ½ cup of activated charcoal, rinsed (available at aquiarium supply stores)
• Sponge
• Coffee filter
• Paper clip
• Drinking straw
• Cotton ball
• 2-liter pop bottle, cut in half
• Rubberband
• Tape (electrical or duct)
• Panty-hose
• Modeling clay or plumbers putty
• Scissors
• Yarn, 12” long

Contamination Materials

• Large bucket willed with water and the following items:
• Food coloring, about 6-8 drops
• Raisins or dried beans, about 1/2 cup
• Soil, about 1/2 cup
• Baking soda, about 3 tablespoons
• A paper plate, torn into small pieces
• A handfull of natural items like sticks, twigs, leaves, grass, pinecones, etc.

Advance Preparation

1. Decide how many teams you want and how many students will be on each team. We recommend smaller teams of 2-3 students as to allow all students the opportunity to get involved.
2. Each team will need one 2-liter pop bottle, cut in half. Take the top portion of the bottle and turn it upside down and place it in the bottom portion. The filter will be built inside the inverted, top portion of the bottle. The base portion will act as a reservoir and collect the water that runs out of the filter.
3. Now make the contamination liquid that will be poured through the students filter. Take the bucket of water and mix in the “contamination materials.” The food coloring represents chemicals, the raisins represent animal/human waste, the potting soil represents earth, the baking soda represents road salt, the soy sauce represents motor oil, and the torn paper plate represents litter.

Activity Steps

1. Discuss filtration systems and wetlands with students.
2. Provide each team with the filter materials and explain to them that they have been hired by a water treatment plant to design the most efficient water filtration system possible with the materials supplied. The teams may only use eight items, not counting the pop bottle, to construct their filtration device. Grant them fifteen minutes to discuss and construct their filter.
3. At the end of the fifteen minutes, have each team share with the group which materials they built their filter from and why they decided to use each item. Then pour the “contaminated” water on to the top of each of the filtration systems. This part can be messy, so it’s best to move outside. The team that has the clearest, most debris free water in its collection base is the declared the winner.
4. Compare and contrast the outcomes of each team’s filtration system. Ask each team what they would change if they could re-build their filtration system.

Activity Source
The Filter Challenge is included in the activity guide "Making Discoveries," (under the title The Groundwater Challenge) and is published by The Groundwater Foundation. If you are interested in more activities based on environmental issues, see our Online Catalog or contact The Groundwater Foundation at 1-800-858-4844.