In this activity, students investigate different methods (aeration and filtering) for removing pollutants from water. They will design and build their own water filters.
Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.
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- Colorado: Science
- a. Develop, communicate, and justify a procedure to separate simple mixtures based on physical properties (Grade 5)  ...show
- International Technology and Engineering Educators Association: Technology
- B. Waste must be appropriately recycled or disposed of to prevent unnecessary harm to the environment. (Grades 3 - 5)  ...show
- Next Generation Science Standards: Science
- Generate and compare multiple possible solutions to a problem based on how well each is likely to meet the criteria and constraints of the problem. (Grades 3 - 5)  ...show
- Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved. (Grades 3 - 5)  ...show
- Identify the pollutants in a water sample using sight and smell.
- Explore what types of pollutants are removed from water by aeration and filtration.
- Design, build and test a water filtration system.
- Understand the role of engineers in water treatment systems.
- 1 copy of the Data Collection Worksheet set
- 1 2-liter bottle cut in half horizontally, as in Figure 1. (Note: Ask students to bring these in or visit the recycling center near you. Be sure to wash the bottle before use. These can be the same ones that you used in the This Landfill is a Gas Activity of Lesson 4.)
- 1 3-inch square of mesh (fine nylon screen, fine cheese-cloth, etc.)
- 1 rubber band
- 1 spoon or other stirring utensil (chopsticks work well)
- Filter materials: - Filter paper or large coffee filter (at least 6" in diameter) - 6 cotton balls - ~6 cups soil - ~6 cups sand - 1 dozen large and small pebbles (total) - ~6 cup activated charcoal (used for potting plants and in aquariums)
- 1 aquarium aerator or a mechanical stirrer/mixer (aeration pumps for fish tanks work well)
- Measuring cups
- 2 large jugs/jars (approximately 1 gallon size – plastic gallon milk jugs with lids are great), for mixing/storing "Polluted Water" (recipe follows)
- "Polluted Water" (made by mixing the following, in amounts at your discretion): - Water (enough to fill the jugs/jars approximately ¾ full) - Green food coloring - Dirt - Organic matter (grass clippings, orange rinds, etc.) - Dishwashing detergent - Vinegar - Baking soda - Salt - Pepper - Pieces of polystyrene foam (foam peanuts) - Small pieces of newspaper - Your own ideas
Before the Lesson
- Prepare the "polluted" water sample and let it ripen in a sunny spot for a day or two. (Note: This can also be done as a class demonstration so that the students know exactly what is in the water. If you decide to do this, ask the students to write down the "ingredients" and make observations about the "polluted" water as it changes. They should use sight and smell, but do not let them taste the mixture.)
- Place the aerator/mixer in one sample of "polluted" water and let it sit overnight before Part 1. You will probably need to aerate a large sample of water for a day or so before Part 2 (depending on how many groups choose to use aerated water for their best filter). (Note: Aeration is the process of adding air to water. It is often done as part of the water purification process. This allows many harmful organic pollutants to react with the oxygen and change into carbon dioxide and water.)
- Be sure to mix the solution thoroughly before preparing the student samples.
- Prepare the 2-liter bottles: cut them in half horizontally. Place a square of mesh over the bottle opening and secure it with the rubber band. (If you use cheese-cloth, you will need to replace it before Part 2.)
- Make copies of the Data Collection Worksheets, 1 set per group.
- Make a transparency or large chart of the class data section for use in Part 1.
- Review the water cycle with the students. Pay special attention to where the water can be purified. The Magic School Bus – Wet All Over: A Book About the Water Cycle, by Joanna Cole and Pat Relf (New York, NY: Scholastic Books, Inc., 1996) has a great description.
With the Students
- Divide the students into groups of 3.
- Distribute a Data Collection Worksheet set to each group.
- Remind the students that they are now working for the Clean Water Environmental Engineering Company and have been asked to design a new water filtration system for a small community with a polluted water supply. First, the company is going to look at different types of filter material to determine which ones work well. Then each group in the company will design a filtering system to clean up the polluted water.
- Give the following supplies to each group: a pre-cut 2-liter bottle, a ½-¾ cup (100-200 mL) sample of the "polluted water" (in a beaker or cup), one type of "filter" (one group will not get a filter as they will test the mesh only), and a spoon.
- Ask each group to draw a picture of the "polluted water." Ask them to describe in words what it looks and smells like. Remind them to gently stir the solution and record observations of that as well. They should record their answers on the Data Collection Worksheet. Remind students that they should never, ever taste the solution.
- Ask students to write down a prediction for what they think their particular filter material will do. (There is a space for this on the Data Collection Worksheet.)
- Ask students to set up their filters by placing the filter material into the inverted 2-liter bottle top, as in Figure 2. (Note: the filter should be place in the end of the bottle with the neck; it will function like a funnel. Use the other half of the bottle as a stand.) They should draw a picture of their set-up on the data sheet.
- Ask students to gently stir the polluted water and then slowly pour it into the filter. (Note: The group with the filter paper will need to be careful not to pour liquid above the top of the filter.)
- They should observe what happens during the filtration. Some filtrations will take longer than others. They should record their observations and draw a picture of the filtered water on their data sheet.
- After all the groups have collected their data, share the results as a class (fill in the information on the transparency or chart you made earlier). Students should record everyone's results in their class data section on their worksheet as well.
- As a class, look at the aerated sample. Discuss what aeration is and how it works (see aeration explanation in the Before the Lesson section).
- Ask students to work in their engineering design groups to design the best water filtration system given the filter choices and a choice of aerated or non-aerated water. There is a place on the Data Collection Worksheet for them to record and explain their choices. (They can use as many of the filtering items as they want.)
- Collect all supplies and dispose of used items properly. (The 2-liter bottles will need to be rinsed and saved for Part 2.)
- Have students break into their groups assigned during Part 1.
- Give each group a prepared 2-liter bottle, ½-¾ cup (100-200 mL) of the "polluted water" in a beaker or cup (aerated or non-aerated, whichever they chose), and a spoon.
- Distribute the filter materials as needed. (Note: Assign a specific "materials" person from each group to collect the supplies from a central location in the room.)
- Ask the students to build their groups' water filter system and draw a picture of it on the Data Collection Worksheet.
- Ask students to gently stir the polluted water and then slowly pour it into the filter. (If filter paper has been used, students will need to be careful not to pour liquid above the top of the filter.)
- They should observe what happens during the filtration process. (Note: Some filtrations will take longer than others; students should not panic if their filtration takes longer than another groups'.) Groups should record their observations and draw a picture of the filtered water on their Data Collection Worksheet.
- Ask students to record their results and complete the discussion questions on the Data Collection Worksheet. Have them compare answers with a group member.
- After all the groups are finished, label and line up the samples. Ask each group to present their filter system to the class (aka Clean Water Environmental Engineering Company). Have a class vote and discussion about which water is the cleanest and why.
Pre-Activity Assessment: Part 1
Pre-Activity Assessment: Part 2
Activity Embedded Assessment: Parts 1 and 2
Post Activity Assessment: Part 1
Post Activity Assessment: Part 2
Cole, Joanna and Relf, Pat. The Magic School Bus – Wet All Over: A Book About the Water Cycle, New York, NY: Scholastic Inc., 1996 (ISBN 0-590-50833-4).
Glencoe Science: An Introduction to the Life, Earth and Physical Sciences, Student Edition, Blacklick, Ohio: Glencoe/McGraw-Hill, 2002.
Hassard, Jack. Science as Inquiry – Active Learning, Project-Based, Web-Assisted, and Active Assessment Strategies to Enhance Student Learning, Tucson, AZ: Good Year Books, 1999 (ISBN 0-673-57731-7).
Lucas, Eileen. Water: A Resource in Crisis, Chicago: Children's Press, Inc., 1991.
Prentice Hall Science. Ecology Earth's Natural Resources Activity Book, New Jersey: Prentice Hall, Inc., 1993.
Spurling Jennett, Pamela. Investigations in Science – Ecology, Westminster, CA: Creative Teaching Press, Inc., 1995.
Stille, Darlene. The New True Book – Water Pollution, Chicago: Childrens Press, Inc., 1991.
Amy Kolenbrander, Jessica Todd, Malinda Schaefer Zarske, Janet Yowell
© 2005 by Regents of the University of Colorado.
Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Last modified: March 5, 2015