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STEM ready

Water Filtration

Driving or Multi-dimensional Question:

How can we, as environmental engineers, create a filtration system to clean polluted water?

Unit Summary:

Water quality is imperative for all living things. TVA monitors water conditions and supports a broad range of clean-water initiatives. They are committed to clean water for their region. However, TVA doesn’t have the power to regulate water pollution, but they care deeply about the quality of the water.

In this PBL, students will analyze and discuss environmental stewardship along with the role environmental engineers play in maintaining water quality. Students will explore the importance of water quality while using ordinary materials to design portable water filters. Filtration systems will be used to clean polluted water.

Hook Event:

In this PBL, students will focus on the importance of clean water. Students will use the engineering design process to design and build a portable water filtration system to remove contaminants from “polluted” water.

Begin the lesson by created a “polluted” water bucket. Fill a large bucket with water and start adding various items to represent water pollution.
-Food coloring the represent chemicals
-Torn pieces of paper to represent litter
-Soil or dirt
-Dried beans to represent human/animal waste

As you add these items, explain to the students that we will think like environmental engineers to design and create a water filtration system to filter the polluted water.

Culminating Event:

Students will design a solution to a real-world problem, water pollution, and present their design to the class. A rubric will be used to assess mastery.


Science Standards:

3.ETS1.1 Design a solution to a real-world problem that includes specified criteria for constraints.

Math Standards:

3.NF.A Develop understanding of fractions as numbers.

ELA and Other Standards:

SL1 Engage effectively in a range of collaborative discussions.
3.67 Read and interpret information about the impact of people on the environment.

Daily Activities

For more information on this lesson please  see the Lesson Resources below

DescriptionResources and Materials
Activity One

Environmental Stewardship refers to protecting the environment through recycling, conserving, regeneration, and restoration. Throughout this PBL students should focus and list ways they can become good stewards of the environment. They will use their thoughts to think like environmental engineers to solve a real-world problem, polluted water. The following questions should be addressed:

-Why is it important to have clean drinking water? 

-What does a filter do?

-Is water safe to drink after filtration? (Introduce purification as an extension)


What is the problem?

What do you already know?

What have others done?

What are the constraints?

After the hook event, students will begin working through the Engineering Design Process to build a broader understanding about filtration. Students will begin by defining the problem and researching to see what others have done. During this step, the teacher will need to list the constraints for the design challenge. Students will use the “ASK” planning sheet to record their responses. 


-Work with a group of 2-3 students

-Build a portable water filtration system using only one plastic bottle (2-liter or 10-ounce bottle)

-Analyze materials and pick no more that 4 items for filtration

-Set time limit for the create phase (30 minute build time suggested)

Resources/Materials Needed:

-Plastic 2-liter bottle

-Plastic 16-ounce bottle




-Coffee Filters

-Cotton balls

-Panty hose




-Tape (masking or duct) 

Activity Two


-Brainstorm ideas.

-List possible solutions.

-Research to find out more.

-Choose the best solution.

During the Imagine phase, students will research filtration systems and begin to brainstorm ideas for their design. Allow time for students to research commercial and homemade filtration systems. Teams will list possible solutions to the problem. After multiple solutions have been discussed, student teams will choose the best solution before moving to the planning phase. 

Activity Three


-Draw a diagram.

-List supplies you will need.

-Make a list of the steps you will take.

After a solution has been chosen, students will begin to plan their design. Students will use the “PLAN” template to list materials needed along with creating a diagram of their portable filter. Students will need to clearly label each material in their filter. Students will list materials as a fraction to show accurate representation and amounts to be used. Ask the following questions:

-What materials did you use and why?

-What items (contaminants) do you predict will be caught by your filter?

-Will you place materials in a particular order?

Activity Four


-Follow your plan.

-Build a prototype.

-Test  your design. 

Student teams will now follow their labeled diagram to construct their portable water filtration system. After designs have been constructed by all teams, students will use their filter to test the “polluted” water. Students will pour “polluted” water in their filter and observe the effectiveness of their design. Discuss the results after each team has tested their filter. 

-Were all contaminants removed?

-Were natural or manmade contaminants easier to remove?

-If you changed the order of your layered materials, would you remove more contaminants?

Activity Five


-What worked?

-What didn’t work?

-Make changes.

-Redesign and test again!

Students will now redesign their water filters. Students should make changes based on what worked or didn’t work during their original test. Allow teams time to work on a new plan before creating their final filter. Test filters again and compare results. 


Technology Integration: A variety of technology will be used throughout the daily activities. Students will use web based devices to research their filtration systems, student made systems, and capstone videos.

Community PartnersContribution to Learning ExperienceContact Information
TVA Environmental information, resources, and career guest speakers
Local Clean Commission OrganizationGuest speaker, provide resources for recycling and how to stop pollution 
Local TN Department of Environment & ConservationStarting point for environmental questions and concerns; provide resources and guest speaker 

Capstone Presentation:

Students will present their final filter design and explain the effectiveness of their design. Students will analyze materials and discuss the importance of each material in their filter.

Students will create an advertisement to showcase their water filtration system. Students will choose between a billboard, newspaper or video advertisement. Students will create a catchy name for their filter and use graphics to grab the attention of their intended customers.

Lesson Resources