Teachers TryScience

You Are What You Drink!

Mar 21 2011

Source: TeachEngineerin...

Summary Information

Keywords:

pollution, water, filtration, filter, water treatment, environmental engineer, contaminants, disinfection, public health

Topic:

Earth Science

Biology

Chemistry

Workplace Skills:

Raising Questions

Secondary Research

Teamwork

Estimated Time Required:

1-2 hours

Target Grade (Ages):

Grade 6 (Ages 11-12)

Diversity Indicators:

This lesson is appropriate for all learners and encourages different ways of thinking and learning.

Watch this Lesson in Practice

Tab Wrapper

LESSON

Goals and Prerequisites

Goals:

To introduce students to some factors that affect drinking water
To expose students to the role engineers play in water treatment
To encourage students to explore and design water filtration systems

Prerequisites:

Be able to:

Develop a hypothesis
Apply the scientific method and design engineering principles.

Instructional Objective(s)

After this lesson, students should be able to:

Identify several processes used to treat water to make it safe to drink
Use vocabulary to help explain drinking water treatment
Design and build a model filter and compare it to processes used by engineers in water treatment
Test and make observations on filter effectiveness
Use data from observations to construct a reasonable explanation of drinking water treatment through a filter.

Instructional Resources

Background:

Before starting this lesson, you may want to watch the video below entitled What is Engineering.

What is Engineering

How is Drinking Water Treated?

The largest cities in the United States get their water from surface water - lakes, rivers and reservoirs. Water taken from any surface source usually has some amount of debris (i.e., sticks, leaves, dirt) in it. It can also contain small amounts of pathogens or contaminants. "Raw water" is sent to a drinking water treatment facility to make it potable. At the drinking water treatment facility, the water flows through many different processes to remove any contaminants.

Point source pollution is the leading cause of water pollution. Point source pollution is pollution that comes from a definite source, such as: direct industrial discharge and dumping, accidents, deep-well injection, leaky landfills, leaking underground storage tanks, abandoned hazardous waste sites, septic tanks, etc. Point source pollution can usually be measured and there is strict government regulations on its discharge (i.e., permits must be obtained from the local government for permission to discharge such pollutants into the environment).

Nonpoint source pollution follows point source pollution in terms of its cause for polluting our waters, but is still a major contributing factor. Nonpoint source pollution is described as water that runs over the ground and picks up — and then carries away — natural and human-made pollutants. This water is then deposited into our lakes, streams, coastal waters and even underground sources of drinking water, resulting in harmful effects on drinking water supplies, recreation and wildlife. Sources for nonpoint source pollution include: agricultural runoff, urban runoff, mining, logging, grazing, etc.

People have been treating water to make it safe to drink for a long time. Originally, people thought water was safe to drink if it was clear, so they worked to remove turbidity. Federal regulation of drinking water in the United States started in the early 1900s, but regulation did not become strict until the Safe Water Drinking Act of 1974. This law underwent changes in 1986 and 1996 and is now governed mostly by the United States Environmental Protection Agency (US EPA).

Today, environmental engineers are concerned about making drinking water safe for people to drink. They design the treatment facilities for drinking water processes, and they are responsible for getting rid of the contaminants and bacteria in untreated water that may make people sick. There are several processes that they use, including: coagulation, in which a powdery chemical, called a coagulant, is added to the water; and flocculation. After clumps or flocs begin to form, the water flows into a large basin so that the big clumps can settle to the bottom, where they are removed. Sedimentation is the settling process that removes most of the big particles from the water, but there may still be some small particles left in the water. To remove these remaining particles, the water flows through a filter. Lastly, engineers in the United States also disinfect the water. Disinfection is often performed by adding chlorine to the water to kill germs. After all these steps, it is now clean enough to drink!

The following video explains what IBM engineers are dong to protect our water supply. You may choose to share this with students to help inform the lesson:

Mad Science: Making Water Smarter

In addition to designing ways to treat water, environmental engineers are called on when water quality in a drinking water facility changes or the design/machinery is not cleaning the water properly. These engineers figure out how to fix the problem and clean up the contaminated water.

Water engineering is a large and diverse branch of civil and environmental engineering. In one way or another, civil engineers are involved in almost every part of the water cycle – from the time water falls as rain until it is returned to the sea. Water engineers design and help build dams to create water storage reservoirs; use hydropower to generate electricity; and divert water through tunnels, canals and pipelines to provide irrigation, transport water to cities, and supply safe drinking water to homes and industries. To learn more about what civil engineers do, visit the Institution of Civil Engineers.

Materials:

Each group should have:

0.5 liter (500 mL) plastic water or soda bottle
½ cup granulated activated carbon (GAC) (available from chemical supply stores or pet supply stores in the aquarium section)
2-3 cotton balls
Jar (smaller in diameter than the 500 mL bottle so that the water bottle can be supported in the jar without falling through)
Nylon stockings
Styrofoam or other absorbent material

For the classroom to share (and teacher to use):

Drill with small diameter bit
Kitchen knife or scissors
3 tsp. of chocolate powder mix (used for making instant chocolate milk)
Water (enough water for each bottle to be filled up 3-4 oz.)
Pitcher or bucket for mixing powdered chocolate and water
4-5 cups of sand
50+ marbles
Something to represent pesticides such as food coloring
Vegetable oil, to represent automobile waste
Litter such as paper or plastic packaging

Procedure:

Before the Activity

With a straight knife or a pair of scissors, cut off the bottoms of each empty 0.5 liter bottle and discard.
Using the drill, make two holes in each bottle screw top. Although this step is not required, the water flow will be slower which will create less mess in the classroom.
Prepare a mixture of "dirty" water by mixing two or three teaspoons of chocolate powder and the cold water in the pitcher. Don't worry if the powder makes lumps at the top of the mixture. You can also add other “pollutants” like vegetable oil, litter, or food coloring.
Construct one or two filters as examples: turn one plastic bottle upside down, with the cut opening to the top, and place a cotton ball in the lid. Screw the lid back onto the bottle. This filter can be used as the control filter for students, by pouring the mixture into the bottle and watching the chocolate/water mixture pour out. Create another filter the same way, but add whatever mixture of cotton, sand, nylon and marbles that you would like to the filter.

With the Students

Questions to Ask

To generate discussion with your class, you may want to begin by asking the questions below. You may also want to watch the following video:

Asking Good Questions video
How many of you know someone who filters their tap water?
How many of you know someone who buys bottled water?
Have you ever been in the woods or mountains and drank water from a river after being filtered by a small pump? Why do we do this? Does the water look contaminated? (Answer: sometimes, yes!)
Show the students a glass of muddy water. Can you hypothesize where it came from? Does anyone know what is in the water? Would you want to drink this if it came from your kitchen tap?

Introduction

You may want to share the information from the Background section to introduce the lesson to students. The following video on Teaching with Current Events may help inform your instruction:

Teaching with Current Events

Let students know that unfortunately, naturally pure water does not exist. All water sources carry small particles that have been absorbed or dissolved in the water as it passes over river beds, rocks and soil. Today, students will investigate drinking water filters by taking samples of muddy water and using the available materials to clean up the water as much as possible.

Begin with the Pre-Assessment

In-Class Procedure

Separate the class into groups of 4 to 5 students. Explain to the students that they are going to be environmental engineers designing a water filter for a drinking water treatment plant. Tell students that their goal is to use any combination of the available materials to make the cleanest water. However, they must each have a cotton ball in their bottle lid. For more information about working with students in groups, you may want to watch the following video:

Group Work video
Have students make predictions on which filter layer will be the most effective at cleaning the water and why.
When each group has finished creating their filters, pour about 2" thick (approximately ½ cup) of granulated activated carbon (GAC) on the top of their layers. Now the filters are ready to be used.
Have students place their filters with the caps downwards on the top of their glass jars.
The teacher should pour the “polluted” mixture into the prototype filters for each group. Students should observe the "clean" water move from the bottom of their filter into the jars. When the filtration is done, ask students to take their jars and filters to a location where light can illuminate the new mixtures. What happened to the water when it was filtered? (Answer: It turned clearer, less water was remaining, etc.)
Have the class vote on who created the filter that cleaned the water the most. If time allows, try to have a discussion on why the winning filter was the most effective, and possible ideas to make the filter even more effective the next time. Discuss the idea that water filtration is a complex process and often requires multiple filtration methods to deal with different types of pollutants

Safety Notes

The teacher should pre-cut and pre-drill the bottles, rather than allowing the students to handle the knife and drill.

Troubleshooting Tips

If you cannot find granulated activated carbon (GAC) in chemical stores, carbon for aquarium filters sold at pet shops can be used.
You can add other filter materials for students to use, including paper towels, coffee filters and gravel.

Extensions

Slice open a water filter for students and have them study the components in it. Discuss with the students the concept of adsorption or the capability of a solid to attract to its surface molecules of other solid or gaseous materials.

Have each team filter water using a different individual layer (investigate with sand OR marbles, etc.). Each team should record their observations of that type of filter on a group chart on the board. From the different observations of filter ability, students can reason why they choose the layers of materials that they did for their final filter. (For example, maybe marbles will produce darker filtered water because they let fine particles pass through; however, coupled with sand, this filter did not let fine particles through, and thus this may be a good combination for a final design.)

Take a tour of your local drinking water treatment facility, or ask someone who works there to visit your class to explain how it works.

Ask students to answer the following questions based on Internet research: Do people in other countries treat their water? What are some inexpensive ways to make water safe to drink (Example: http://www.sodis.ch/, http://www.potpaz.org/pfpfilters.htm)

Cleaning water with dirt? Have students conduct an experiment using soil to learn how dirt can work as a filter: http://soils.gsfc.nasa.gov/filter/filter.htm.

Other suggestions to extend this activity can be found at TeachEngineering, including the original You Are What You Drink! activity.

Assessments and Rubrics

If you are interested in learning how to make your own rubric for this or other lessons, you may be interested in watching the How to Make a Rubric video below.

How to Make a Rubric

Or, you can choose to use or customize the one created for this lesson plan below.

You Are What You Drink Rubric (XLS)

You Are What You Drink Rubric (PDF)

Pre-Activity Assessment

Know / Want to Know / Learn (KWL) Chart: Before the lesson, ask students to write down in the top left corner of a piece of paper (or as a group on the board), under the title Know, all the things they know about drinking water filters. Next, in the top right corner, under the title Want to Know, ask students to write down anything they want to know about drinking water filters. After the lesson, ask students to list in the bottom half of the page, under the title Learned, all of the things that they have learned about drinking water filters. Ask students to name a few items and write them on the board.

You might want to review the video below entitled KWL to help you with the pre-activity assessment.

KWL video

Activity Embedded Assessment

Drawing: Have the students draw a picture of their drinking water filter. Ask them to draw the different layers in their picture and try to name the layers as well as what particles that layer will remove as best they can. Inform them that this is what an engineer would do when deigning a new product.

Post-Activity Assessment

Show and Tell: Have the students "show and tell" to the rest of the class the filters they created, explaining their work to the other students. Ask the students to compare each others' filters and brainstorm other materials or construction orders that they could use to improve their filters.

Re-Design Practice (if time allows): Have the students list any design or fabrication changes they would make to their filters on a piece of paper or in their journals. They can also draw a picture of their new design. Emphasize that engineers often re-design their products several times before getting it right.

Student-Generated Questions: Have each student come up with one question of their own about filters and/or drinking water to ask the rest of the class. Be prepared to help some students form a question. If the answers to the questions are not available, encourage the students to search the EPA (http://www.epa.gov) website and to bring those answers back to the classroom to share with the other students.

Roundtable: Have the class form into teams of 3-5 students each. Ask the class a question with several possible answers. Have the students on each team make a list of answers by taking turns writing down ideas on a piece of paper. Students pass the list around the group until all ideas are exhausted. Have teams read aloud the answers and write them on the board. A question you might want to pose could be:

How would you remove or minimize pollutants in drinking water?

Possible Answer: The first step in treating surface water is to add a powdery chemical, called a coagulant, to the water. Coagulants make the particles in the water stick together in clumps. When particles stick together, they grow into clumps called flocs, so this gentle mixing process is called flocculation. After the flocs begin to form, the water flows into a large basin so that the big clumps can settle to the bottom, where they are removed. This settling process, called sedimentation, removes most of the big particles from the water. To remove any of the remaining smaller particles, the water flows through a filter, made of a special kind of sand. After flocculation, coagulation, sedimentation and filtration, most of the contaminants are removed from the water. However, since everyone needs to drink water, disinfection is often performed by adding chlorine to the water to kill any remaining germs.

External Resources

Information Video

The following video explains what IBM engineers are dong to protect our water supply.

Mad Science: Making Water Smarter

Web Sites

Institution of Civil Engineers: The Little Book of Civilisation looks at the amazing ways civil engineers overcome the challenges of creating and maintaining infrastructure for us, and for future generations.

Nepal Water for Health: A look at water quality and treatment in the country of Nepal

New JerseyAmerican Water Works Association, Kids' Water Zone: Water Treatment and Distribution to Your Home

TeachEngineering Digital Library: Original You Are What You Drink! activity

U.S.Environmental Protection Agency: The History of Drinking Water Treatment

U.S.Environmental Protection Agency: Water on Tap: What you need to know

U. S. Geological Survey: Water Education Posters (free)

Credits

This material was adapted from the You Are What You Drink lesson, created through the Integrated Teaching and Learning Program at the College of Engineering and Applied Science at the University of Colorado at Boulder. The TeachEngineering Digital Library is a free, online collection of teacher-tested K-12 engineering activities, lessons and units aligned to educational STEM standards, funded primarily through the National Science Foundation

RESOURCES

Original Resources

Asking Good Questions (MP4)

Group Work (MP4)

How to Make a Rubric (MP4)

KWL (MP4)

Mad Science: Making Water Smarter (MP4)

Teaching with Current Events (MP4)

What is Engineering (MP4)

You Are What You Drink Rubric (PDF)

You Are What You Drink Rubric (XLS)

Lessons In Practice

You Are What You Drink! Introduction

Introduction

You Are What You Drink! Lesson

Lesson

You Are What You Drink! Reflection

Reflection

Contributed Resources

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Water Filtration R.A.F.T Assessment

E.L.A. Assessment for You Are What You Drink!

Water Filtration R.A.F.T Assessment Student piece

E.L.A. Assessment for You Are What You Drink! student work product

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Comments

Designing a Water Filtration System

This is a great lesson, easy to modify if need-be. Lots of fun!

i liked this too much, i will

i liked this too much, i will try to practice this experience in my classroom.

wondreful

Dime lo que bebes y te diré

Dime lo que bebes y te diré quién eres.... excelente proyecto para realizar en aula, creando en los alumnos aprendizajes significativos para su vida presente y futura, que les arroje un aprendizaje a aplicar en su vida cotidiana cuando se les presente una problemática como la que plantea al beber agua sucia y con estos aprendizajes los alumnos podrán realizar un filtro logrando así la interiorización de palabras como: contaminación, agua, filtrado, filtrar, tratamiento del agua, ingeniero ambiental, contaminantes, desinfectar, salud pública.Gracias por compartir... :)

WOW!, I loved this lesson, I

WOW!, I loved this lesson, I find it so useful, the way you explain how to do the lesson in the classroom, the information that you provide, I was thinking in add some more inforation that can help my students indentify the new voacbulary and understand why it is importat follow the sings if the water is not clean or if they have to do something else before drinking it. I hope they get new ideas to try to have a better world, and more than that I hope they can realize that they can also be those who going to change the world, have nice results making something to clean the water.

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