Learning Resource Type

Lesson Plan

Filtered or Not Filtered That's the Question!

Subject Area





Students will collaborate, design, and construct a device that filters contaminated water. 

This lesson was created as part of the 2016 NASA STEM Standards of Practice Project, a collaboration between the Alabama State Department of Education and NASA Marshall Space Flight Center.

    Science (2015) Grade(s): 5


    Design solutions, test, and revise a process for cleaning a polluted environment (e.g., simulating an oil spill in the ocean or a flood in a city and creating a solution for containment and/or cleanup).*

    Unpacked Content



    • Solution
    • Test
    • Revise
    • Polluted
    • Environment
    • Engineer
    • Technology


    Students know:
    • Human activities in agriculture, industry, and everyday life can have major effects, both positive and negative, on the land, vegetation, streams, ocean, air, and even outer space.
    • Individuals and communities are doing things to help protect Earth's resources and environments.
    • Research on a problem should be carried out before beginning to design a solution.
    • Testing a solution involves investigating how well it performs under a range of likely conditions.
    • At whatever stage, communicating with peers about proposed solutions is an important part of the design process, and shared ideas can lead to improved designs.


    Students are able to:
    • Use grade-appropriate information from research about a given problem, including the causes and effects of the problem and relevant scientific information.
    • Generate at least two possible solutions to the problem based on scientific information and understanding of the problem.
    • Specify how each design solution solves the problem.
    • Share ideas and findings with others about design solutions to generate a variety of possible solutions.
    • Describe the necessary steps for designing a solution to a problem, including conducting research and communicating with others throughout the design process to improve the design [note: emphasis is on what is necessary for designing solutions, not on a step-wise process].


    Students understand that:
    • Engineers improve existing technologies or develop new ones to: increase benefits, decrease known risks, and/or meet societal demands.

    Scientific and Engineering Practices

    Constructing Explanations and Designing Solutions

    Crosscutting Concepts

    Systems and System Models

    Primary Learning Objectives

    The students will:

    • design and build their own water filtering system.

    • collect data to compare water before and after filtering.

    • develop a conclusion based upon the results of this experiment.

    • compare individual results to class results to look for patterns.

    Additional Learning Objective(s)




    Pre-lesson Instructions (30 minutes prep time)

    • Students should work in groups of 3 or 4.

    • Write the names of the 7 different filtering materials on 7 individual small slips of paper and place them in a hat or basket. In addition, write “free choice” on several small slips of paper. Add enough “free choice” slips for each group to choose a total of 3 filtering materials (suggested option).

    You may also place the materials as a "store" and students have a certain price range they can use for the store.

    • Gather materials for this activity. Each filtration material needs to fill the water filtering system to a depth of 5–8 cm. There should be enough of each filtration material for several groups to use. Make sure to have extra material for students to choose their “free choice” options.

    • Wad up enough coffee filters for multiple groups to use as a filtration layer (You may leave this out and have the filters in the store setting making them develop this strategy on their own).

    • Rinse the activated charcoal granules in advance to remove the dust. Put the granules in a mesh bag (pantyhoses work well) and rinse with tap water.

    Note: To increase rigor, you may give them the contaminated water and bottle filter base. All other materials will be used by each determining group. This allows for higher thinking and creative skills.

    Filtering system structure: (one per group)

    • Punch a hole in the top of each cup, just below the rim to avoid a vacuum (optional). * Use this diagram.
    • Remove the labels on the 2-liter bottles and then cut off the bottom of the bottle, just above the curve of the bottle.
    • Construct the structure of the water filtering system by covering the mouth of the bottle with at least 10 layers of cheesecloth and secure with a rubber band.

    To increase rigor, you may allow the students to determine how to place and use the filter design in their groups independently. 

    Make “Contaminated Water”:

    • Test your tap water before making the contaminated water solution. You want to start this solution with “clean water." Your clean water should have a pH between 6.5 and 7.5. If your tap water is not between pH 6.5 and 7.5, then use store-bought drinking water.
    • Mix 1 part Italian salad dressing (vinegar and oil with seasonings, shaken) to 5 parts water in a large, clean container.
    • Make enough contaminated water for each group to have about 500 ml.
    • Note the pH of the contaminated water, it should be around 4. If needed, you can add vinegar to the contaminated water to drop the pH.

    Note: Reserve enough clean water (either tap water or store-bought drinking water with a pH between 6.5 and 7.5) so that each student group has about 500 ml. 

    Instructional Procedure

    1. Remind students about pH including base, neutral, and acid. Also reference pH testing using litmus paper and pH color charts.

    2. Review the problem with the students.
    Problem: What can I do to make clean water?

    3. Pass out a copy of Observation and have the students read and discuss in their groups.

    4. Encourage your students to discuss and make observations about this topic by completing the first two columns in the KWL (KNOW/WANT TO KNOW/LEARNED) chart in their journals. Use the KWL chart to help students organize prior knowledge, identify interests, and make real-world connections. As students suggest information for the “KNOW” column, ask them to share “How they have come to know this information.”

    6. Allow your student groups time to develop a Hypothesis relating to this activity and the “problem question." 
    7. Students will test their hypothesis following this procedure.


    1. Put on your safety glasses.
    (Stress the importance of keeping eye protection on during this lesson.)

    2. Place the bottle upside down with its mouth over the clear plastic cup to catch the filtered water.  Make sure the cup underneath the system is large enough to “catch” the water to be filtered through.

    3. Choose three slips of paper from the teacher.
    Allow each group to choose three slips of paper with designated filtering materials or “free choice” written on them.

    The items written on these papers will be the materials you layer in your water filter. If you choose a “free choice” slip, you and your group may choose what material to use for
    this filtration layer.


    Give students an objective: Their town's water supply is contaminated after a storm. It is their mission to develop a filtration system. The filter must be able to allow water to run through and deposit into the cup. 

    Note: This is where you may limit direct instruction and allow creativity. You may also allow the "store" concept to replace the above distribution technique.


    4. Gather your filtration materials on the paper plates; one on each plate. As a group, decide the order in which to layer your materials.

    5. Fill the bottle with the first filtering material to a depth of 5–8 centimeters (cm).
    Note: Coffee filters and cotton balls will need to be packed down.

    6. Place the second filtering material to a depth of 5–8 cm on top of the first one.

    7. Place the third filtering material to a depth of 5–8 cm on top of the second filtering

    8. Obtain 350 ml of clean water. Observe the properties of the water before you filter it. Use the wafting technique to smell the water. Measure the pH of the water with litmus paper and compare it to the pH color chart. Collect data and record your observations. Remember smelling rules in the science lab and do not taste. This pH measurement will serve as the control.


    When filtering the contaminated water, students will know the contaminated water is cleaned when it matches the control pH.

    9. Run the clean water through your water filtering system to make sure it will allow water to flow through. Students should run approximately 10-16 oz. of clean water through their water filtering system to make sure it will allow water to flow through. Make sure the cup underneath the system is large enough to “catch” all the water passing through.


    Allow students to experiment and determine if their design will work.

    10. While you are waiting for the clean water to run through the water filtering system, draw and label your diagram to match your filtration system. (this can be skipped and allow students to work without determining if the filter works)

    11. Once the clean water has gone through the water filtering system, replace the clear plastic cup with a new one. If the water is sandy, it should be disposed of outside. Otherwise, it can be disposed of in the sink. The cup can be reused in the next step.

    12. Get 350 ml of contaminated water. Observe the properties of the water before you filter it. Check the odor of the water. Measure the pH of the water with litmus paper and compare it to the pH color chart. Collect data and record your observations.

    Remind students to use the wafting technique to smell the water. They should also measure the pH of this water sample. Go over the rules of the science lab regarding smelling and tasting.

    13. Run the contaminated water through your water filtering system. Observe the properties of the water after it has been filtered once and record your observation.

    Measure the pH of the water with litmus paper and compare it to the pH color chart. Collect data and record your observations. Remind students the rules of the science lab regarding smelling and tasting.

    14. Replace the clear plastic cup with a new one. Pour the filtered water back into the water filtering system.

    15. Filter the water again. While the contaminated water is running through the water filtering system, discuss in your group what each layer in your filtration system did to the water.

    16. Observe the properties of the water after it has been filtered for the second time. Check the odor of the water. Measure the pH of the water with litmus paper and compare it to the pH color chart. Collect data and record your observations. Remind students the rules of the science lab regarding smelling and tasting.

    17. After taking all measurements, study the data and draw conclusions by answering the questions.

    Make sure the students compare the properties of their filtered water to the control (clean water) to determine if their contaminated water was “cleaned” by their water filtering system. Using this information, ask students to determine if the data supports or refutes their hypothesis.

    18. Dispose of all material by wrapping in newspaper and placing the material in a trash receptacle.

    • Discuss the answers to your set questions.
    • Have the students update the LEARNED column in their KWL chart.
    • Ask students how their findings relate to the development of new water filtration systems and recycling for space exploration?
    • Ask students “What do you wonder now?” and encourage students to design their own experiments.

    Assessment Strategies

    Assess student knowledge through summative questioning.

     Some sample summative guidelines for questioning:

    • Ask for examples, students talk about outcomes.
    • Summarize what has been said by using the talk moves.
    • Ask students if they agree with statements from peers and have them explain their position.
    • Allow students to discuss the data they have collected. How could this help engineers to develop better ways to filter water?
    • How can data be compared to the other groups?
    • What data supports their outcomes?
    • Ask students about assumptions before, during, and after the activity.

    Observe and assess student performance throughout the activity using the Scientific Investigation Rubric.

    You may also use the activity rubric to grade this activity with or without journal entry.


    Collect and filter other samples of water. Examples are rain water, hand wash water, stream or pond water, etc.
    • Try using other filter media such as Styrofoam™ pieces, potting soil, marbles, and popped popcorn.
    • Have students research how the water in your town is filtered/treated. Maybe take a field trip to the water treatment
    plant, or check into having someone from the water treatment plant come to your classroom.
    • Because weight is always an issue when launching into space (the heavier it is the more it costs to launch it), set
    a weight limit for the filtration device (including filter media). Hold a competition to see which team has the purest
    water (lowest conductivity and most neutral pH) using the lightest filtration device.
    • If equipment is available, have student teams tape/film their work or take pictures. This can then be used to create
    an electronic diary and presentation of their filtration device and results. Have the teams share their creation with
    the class.

    * Use the Design Evaluation Sheet that includes conductivity 


    Students who need extra support should be placed in groups with teammates sensitive to the needs of that student.

    The teacher may need to more closely supervise groups that contain students who are struggling with the concepts of this lesson.

    Approximate Duration

    Total Duration

    61 to 90 Minutes

    Background and Preparation


    At least one day before conducting this experiment:

    • Discuss “purifying and filtering materials” with the class. Encourage students to bring in other materials to add to the list of materials supplied. These will be “free choice” items.
    • Review pH, acid, base and neutral with your students and show them how to pH test using litmus paper. Review the pH color chart.
    • Read the Observation passage to be familiar with the concepts featured in this activity.
    • Review the setup diagram.

    Materials and Resources

    Materials and Resources

    This activity comes form the NASA Education Guide NASA Engineering Design Challenges: Environmental Control and Life Support Systems Water Filtration Challenge.

    Materials Needed:

    • safety glasses
    • 2-liter bottles
    • cheesecloth
    • rubber bands
    • pH testing strips (litmus paper)
    • metric rulers
    • plastic cups
    • paper plates
    • metric liquid measuring cups
    • mesh bag (panty hose)
    • tap water or bottled water Italian dressing (to make gray water)
    • aquarium gravel play sand
    • activated carbon/activated charcoal
    • marbles
    • cotton balls
    • coffee filters
    • packing materials (Styrofoam “popcorn”)
    • lima beans (uncooked)
    • paper towels (for clean up and spills)

    Gather enough for multiple groups to use 7 different materials for filtration layers

    • aquarium gravel
    • play sand (found at nurseries and home improvement stores)
    • activated carbon / activated charcoal (granules, found with aquarium supplies) Note: Activated charcoal is safe and non-toxic. Be sure to check MSDS.
    • marbles
    • cotton balls
    • coffee filters
    • packing materials (Styrofoam “popcorn”) 

    Contaminated Water Ingredients

    Instructions for making wastewater can be found on pages 12 and 13 of the Education Guide.  Italian salad dressing could be substituted for the contaminated water as well.

    • vinegar, distilled
    • food coloring
    • sand
    • salt
    • dirt
    • tap water or bottled water

    Materials needed per group (3–4 students working together)

    • Water filtration system structure (instructions can be found on page 15 of the Education Guide)
      • 2-liter bottle with bottom cut off
      • cheese cloth
      • rubber bands See how to make the water filtering system structure in the Pre-Lesson Instructions Section.
    •  3 filtration materials (to be chosen during the test procedure)
    •  5 litmus paper strips
    •  pH color chart with a range from at minimum 4-10
    •  1 metric ruler
    •  3 large, clear plastic cups (at least 480 ml.) with a hole punched just below the rim (See diagram in the Pre-Lesson Instructions Section.)
    •  3 paper plates
    •  1 metric liquid measuring cup
    •  500 ml of clean water
    •  500 ml of contaminated water (to be made in advance)

    Per student


    Remind students about the importance of classroom and lab safety. Review the rules for smelling (wafting) in the science lab. Students should wear eye protection during this activity.