Filtration Investigation

This lesson focuses on how filtration systems solve many problems throughout the world such as improving drinking water. Through this lesson, students work in teams to design and build a filtration system to remove dirt from water.

  • Learn about engineering design.
  • Learn about planning and construction.
  • Learn about teamwork and working in groups.

Age Levels: 8-18

Materials & Preparation

Build Materials (For each team)

Required Materials (Trading/Table of Possibilities)

  • Plastic or paper cups
  • Straws
  • Cardboard
  • Cotton balls
  • Paper towels
  • Plastic wrap
  • Aluminum foil
  • Rubber bands
  • Toothpicks
  • Sand
  • Aquarium or other small rocks
  • Cornmeal
  • Flour
  • Optional: Charcoal (not recommended for younger students)

Testing Materials

  • 1 plastic container for each team (for collecting 2 cups of filtered water)
  • Supply of “muddy water” (made by taking a quart of water and adding two tablespoons of dirt).

Testing Materials & Process

Materials

  • 1 plastic container for each team (for collecting 2 cups of filtered water)
  • Supply of “dirty water” (made by taking a quart of water and adding two tablespoons of dirt).

Process

Give each team two cups of “muddy” water. Each team tests their design by holding the design over the plastic container and slowly pouring the water into their filtration system. Collect the filtered water in the container for evaluation and comparison across teams.

As a class, assign a “grade of clarity” to each sample of filtered water.  Use the following scoring to determine the results of each team’s work. The team’s with the lower scores have the better filtration systems.

  • 0 = Completely clear (as drinking water might appear)
  • 1 = About a quarter of the dirt remains
  • 2 = About half of the dirt remains
  • 3 = About three quarters of the dirt remains
  • 4 = Completely muddy (as original source water appeared)

Engineering Design Challenge

Design Challenge

You are part of a team of engineers who have been given the challenge of developing a filtration system to eliminate as much dirt or mud as possible from a water sample you have been provided. If your system works, you’ll end up with water that looks completely clear.  How you accomplish the task is up to your team! The team with the clearest resulting water (based on a visual inspection) will have developed the best filter in the class.

Criteria

  • Must eliminate as much dirt or mud as possible.

Constraints

  • Use only the materials provided.
  • Teams may trade unlimited materials.

Activity Instructions & Procedures

  1. Break class into teams of 2-3.
  2. Hand out the Filtration Investigation worksheet, as well as some sheets of paper for sketching designs.
  3. Discuss the topics in the Background Concepts Section. Suggest to student teams that layers of filters – or perhaps many filtration stages – may result in the most effective filtration system. Consider asking students whether one level of filter will work best or if multiple layers might be better. Have them think about how a coffee filter works. How does it keep the coffee grinds from going into the water?
  4. Review the Engineering Design Process, Design Challenge, Criteria, Constraints and Materials.
  5. Provide each team with their materials.
  6. Explain that students must work as a team to design a filtration system to remove as much dirt or sediment as possible from a provided water supply. The team with the clearest resulting water (based on a visual inspection) will have developed the best filter in the class. Be sure to stress that the “filtered” water, no matter how clear, is not suitable for drinking.
  7. Announce the amount of time they have to design and build (1 hour recommended).
  8. Use a timer or an on-line stopwatch (count down feature) to ensure you keep on time. (www.online-stopwatch.com/full-screen-stopwatch). Give students regular “time checks” so they stay on task. If they are struggling, ask questions that will lead them to a solution quicker.
  9. Students meet and develop a plan for their filtration system. They agree on materials they will need, write/draw their plan, and present their plan to the class. Teams may trade unlimited materials with other teams to develop their ideal parts list.
  10. Teams build their designs.
  11. Test the filtration system designs by giving each team two cups of “muddy” water. Each team tests their design by holding the design over the plastic container and slowly pouring the water into their filtration system. Collect the filtered water in the container for evaluation and comparison across teams.
    As a class, assign a “grade of clarity” to each sample of filtered water.  Use the following scoring to determine the results of each team’s work. The team’s with the lower scores have the better filtration systems.

    • 0 = Completely clear (as drinking water might appear)
    • 1 = About a quarter of the dirt remains
    • 2 = About half of the dirt remains
    • 3 = About three quarters of the dirt remains
    • 4 = Completely muddy (as original source water appeared)
  12. Teams should document their score.
  13. As a class, discuss the student reflection questions.
  14. For more content on the topic, see the “Digging Deeper” section.

Extension Idea

Consider setting a budget for the project, assigning a cost to each material, and requiring teams to “buy” materials to create their filtration system.

Student Reflection (engineering notebook)

  1. Did you succeed in creating a filtration system that passed the source water? What “grade of clarity” did you achieve?
  2. What aspect of your design do you think worked best? Why?
  3. What aspect of your design would you have revised if given more time? Why?
  4. What was unique about the design of the filtration system in your class that had the best results on this challenge? How did it work better than yours, if it did, and what would you have done differently if you had seen this design prior to developing your own?
  5. Did you decide to revise your original design while in the construction phase? Why? How?
  6. Do you think that engineers have to adapt their original plans during the construction of systems or products? Why might they?
  7. Do you think your filter would have been able to withstand water running through it for an hour? Why?
  8. Do you think you would have been able to complete this project easier if you were working alone? Explain…
  9. If you could have used a material or materials that were not provided to you, what would you have requested? Why do you think this material might have helped with the challenge?
  10. What was your favorite part of the challenge?  Design Phase?  Building Phase?  Testing Phase?  Why?

Time Modification

The lesson can be done in as little as 1 class period for older students. However, to help students from feeling rushed and to ensure student success (especially for younger students), split the lesson into two periods giving students more time to brainstorm, test ideas and finalize their design. Conduct the testing and debrief in the next class period.

Background Concepts

What is Filtration?

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There are many different methods of filtration, each has a goal of separating substances. Filtration systems are important to providing safe drinking water, to separating materials for many purposes such as research or gathering pure samples of an element. The simplest way to “filter” is to pass a mixture, or solution, of a solid and a fluid (such as water and dirt or mud) through a porous material or system so that the solids are trapped as the fluid passes through. Panning for gold is an example of a filter, where prospectors hold pans with holes punched in the bottom, or fitted with a screen through riverbeds thought to contain gold nuggets. The materials too big to fit through the screen are then explored to see if gold has been gathered. Filtration is used in waste treatment facilities where settling tanks allow for separation. The concept of filtration is found all around us, in community services and everyday items at home. An example is a coffee filter used in a coffee maker. The filter prevents the coffee grounds from reaching a coffee cup, but allows for smaller materials or particles of the coffee to pass through, resulting in a cup of coffee without coffee grounds. There are many different types of filters used in making coffee, some made out of paper, some out of recycled paper, and some using metals coated in gold. In each case, the size of the openings — even microscopic — will determine how much of the particles will make it through.

 

How Gravity Can Help

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Liquids usually flow through the filter by gravity. This is the simplest method, and can be seen by revising the coffeemaker example. The water usually sits in the filter, and then drips down to a receptacle (cup or coffee pot) as a result of gravity. In chemical plants, gravity is also used to separate — and is an economical method as it requires no additional energy.

Filtration Materials and Stages

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Many materials can be used for making a filter…all depending upon the types of liquids, solids, or gases that need to be separated. Some filtration materials include paper, sand, cloth, charcoal, and rocks. Often staged filters are employed…where a liquid, for example, might pass through a series of different filters. In this case, sometimes the first filter will eliminate larger particles, while the second, third, or fourth filter will eliminate smaller and smaller particles of sediment. The image to the right shows a rough filtration system that might be made from sticks using three different stages of filtration…but there are many ideas for systems and engineers must develop new systems based on the challenges they face!

Vocabulary

  • Constraints: Limitations with material, time, size of team, etc.
  • Criteria: Conditions that the design must satisfy like its overall size, etc.
  • Engineers: Inventors and problem-solvers of the world. Twenty-five major specialties are recognized in engineering (see infographic).
  • Engineering Design Process: Process engineers use to solve problems. 
  • Engineering Habits of Mind (EHM): Six unique ways that engineers think.
  • Filter: A device used to remove unwanted parts from something.
  • Filtration System: A process by which impurities or particles are removed from a fluid, either a liquid or a gas.
  • Iteration: Test & redesign is one iteration. Repeat (multiple iterations).
  • Prototype: A working model of the solution to be tested.
  • Staged Filter: Fluid passes through a series of different filters. The first filter will eliminate larger particles, while the second, third, or fourth filter will eliminate smaller and smaller particles of sediment.

Dig Deeper

Internet Connections

Recommended Reading

  • Liquid Filtration (ISBN: 1408626241) Water Reuse (ISBN: 0071459278)

Writing Activity

Write an essay or a paragraph about the type of filtration systems campers might need to employ if they ran out of water and needed to consider drinking water from a stream of unknown water purity.

Curriculum Alignment

Alignment to Curriculum Frameworks

Note: Lesson plans in this series are aligned to one or more of the following sets of standards:  

National Science Education Standards Grades K-4 (ages 4 – 9)

CONTENT STANDARD A: Science as Inquiry

As a result of activities, all students should develop

  • Abilities necessary to do scientific inquiry 

CONTENT STANDARD B: Physical Science

As a result of the activities, all students should develop an understanding of

  • Properties of objects and materials 

CONTENT STANDARD E: Science and Technology 

As a result of activities, all students should develop

  • Abilities of technological design 

CONTENT STANDARD F: Science in Personal and Social Perspectives

As a result of activities, all students should develop understanding of

  • Types of resources 
  • Science and technology in local challenges 

CONTENT STANDARD G: History and Nature of Science

As a result of activities, all students should develop understanding of

  • Science as a human endeavor 

National Science Education Standards Grades 5-8 (ages 10 – 14)

CONTENT STANDARD A: Science as Inquiry

As a result of activities, all students should develop

  • Abilities necessary to do scientific inquiry 

CONTENT STANDARD B: Physical Science

As a result of their activities, all students should develop an understanding of

  • Properties and changes of properties in matter 

CONTENT STANDARD E: Science and Technology

As a result of activities in grades 5-8, all students should develop

  • Abilities of technological design 
  • Understandings about science and technology 

CONTENT STANDARD F: Science in Personal and Social Perspectives

As a result of activities, all students should develop understanding of

  • Populations, resources, and environments 
  • Science and technology in society 

CONTENT STANDARD G: History and Nature of Science

As a result of activities, all students should develop understanding of

  • Science as a human endeavor 

National Science Education Standards Grades 9-12 (ages 14-18)

CONTENT STANDARD A: Science as Inquiry

As a result of activities, all students should develop

  • Abilities necessary to do scientific inquiry 

CONTENT STANDARD B: Physical Science 

As a result of their activities, all students should develop understanding of

  • Structure and properties of matter 
  • Motions and forces 

CONTENT STANDARD E: Science and Technology

As a result of activities, all students should develop

  • Abilities of technological design 
  • Understandings about science and technology 

CONTENT STANDARD F: Science in Personal and Social Perspectives

As a result of activities, all students should develop understanding of

  • Personal and community health 
  • Natural resources 
  • Science and technology in local, national, and global challenges 

CONTENT STANDARD G: History and Nature of Science

As a result of activities, all students should develop understanding of

  • Science as a human endeavor 

Next Generation Science Standards Grades 2-5 (Ages 7-11)

Matter and its Interactions 

Students who demonstrate understanding can:

  • 2-PS1-2.  Analyze data obtained from testing different materials to determine which materials have the properties that are best suited for an intended purpose.

Engineering Design 

Students who demonstrate understanding can:

  • 3-5-ETS1-1.Define a simple design problem reflecting a need or a want that includes specified criteria for success and constraints on materials, time, or cost.
  • 3-5-ETS1-2.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.
  • 3-5-ETS1-3.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.

Next Generation Science Standards Grades 6-8 (Ages 11-14)

Engineering Design 

Students who demonstrate understanding can:

  • MS-ETS1-2 Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.

Next Generation Science Standards Grades 6-8 (Ages 11-14)

Engineering Design 

  • MS-ETS1-3. Analyze data from tests to determine similarities and differences among several design solutions to identify the best characteristics of each that can be combined into a new solution to better meet the criteria for success.

Next Generation Science Standards Grades 9-12 (Ages 14-18)

Engineering Design 

Students who demonstrate understanding can:

  • HS-ETS1-2.Design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems that can be solved through engineering.

Standards for Technological Literacy – All Ages

The Nature of Technology

  • Standard 1: Students will develop an understanding of the characteristics and scope of technology.

Technology and Society

  • Standard 6: Students will develop an understanding of the role of society in the development and use of technology.
  • Standard 7: Students will develop an understanding of the influence of technology on history.

Design

  • Standard 9: Students will develop an understanding of engineering design.
  • Standard 10: Students will develop an understanding of the role of troubleshooting, research and development, invention and innovation, and experimentation in problem solving.

Abilities for a Technological World

  • Standard 11: Students will develop abilities to apply the design process.
  • Standard 13: Students will develop abilities to assess the impact of products and systems.

Student Worksheet

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You are part of a team of engineers who have been given the challenge of developing a filtration system to eliminate as much dirt or mud as possible from a water sample you have been provided. If your system works, you’ll end up with water that looks completely clear. How you accomplish the task is up to your team! The team with the clearest resulting water (based on a visual inspection) will have developed the best filter in the class.

Planning Stage

Meet as a team and discuss the problem you need to solve. You’ll need to determine which materials you’ll request from the many everyday items your teacher has available. As a team, come up with your best design and draw it in the box below. Be sure to indicate the materials you anticipate using, including the quantity you’ll request from your teacher. Present your design to the class. You may choose to revise your teams’ plan after you receive feedback from class.

Design:

 

 

 

 

 

 

 

 

 

Materials Required (list each items and the quantity you expect to use):

 

 

 

 

 

 

 

Construction Phase

Build your filter system. During construction you may decide you need additional items or that your design needs to change. This is ok — just make a new sketch and revise your materials list. You may want to trade items with other teams, or request additional materials from your teacher.

Testing Phase

You will be provided with two cups of “muddy” water by your teacher. You’ll test your filter in a classroom basin and gather the “filtered” water for later evaluation. Be sure to watch the tests of the other teams and observe how they designed their filters, including what materials they selected.

Evaluation Phase

You and your class will be responsible for assigning a “grade of clarity” to each sample of filtered water. Use the following chart to determine the results of each team’s work.

Completely clear

(as drinking water might appear)

 About a quarter of the dirt remains About half of the dirt remains About three quarters of the dirt remains Completely muddy

(as original source water appeared)
0 1 2 3 4

 

Then, evaluate your team’s results, complete the evaluation worksheet, and present your findings to the class.

  1. Did you succeed in creating a filtration system that passed the source water? What “grade of clarity” did you achieve?

 

 

 

 

 

 

  1. What aspect of your design do you think worked best? Why?

 

 

 

 

 

 

  1. What aspect of your design would you have revised if given more time? Why?

 

 

 

 

 

 

  1. What was unique about the design of the filtration system in your class that had the best results on this challenge? How did it work better than yours, if it did, and what would you have done differently if you had seen this design prior to developing your own?

 

 

 

 

 

 

  1. Did you decide to revise your original design while in the construction phase? Why?  How?

 

 

 

 

 

 

  1. Do you think that engineers have to adapt their original plans during the construction of systems or products? Why might they?

 

 

 

 

 

 

  1. Do you think your filter would have been able to withstand water running through it for an hour? Why?

 

 

 

 

 

 

  1. Do you think you would have been able to complete this project easier if you were working alone? Explain…

 

 

 

 

 

 

  1. If you could have used a material or materials that were not provided to you, what would you have requested? Why do you think this material might have helped with the challenge?

 

 

 

 

 

 

  1. What was your favorite part of the challenge? Design Phase? Building Phase?  Testing Phase?  Why?

 

 

 

 

 

 

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