TIME ALLOTMENT:
Introductory Activity: 20 minutes
Learning Activity: Two 50 minute periods
Culminating Activity #1: 50 minutes
Culminating Activity #2: 30 minutes

OVERVIEW:
Water has been around for almost 3.8 billion years and covers more than 71 percent of the Earth’s surface. With all of the water than is present on Earth, only a small percentage of water is available to people (potable water). Of the 280 billion liters/person of water existing on Earth, only 8.4 million liters/person is available for use. This is only about 0.00003 percent of the total water on Earth. This water is constantly being cleaned and recycled for use by living organisms through the hydrological or “water” cycle.
In this lesson, students will learn how the hydrologic cycle (water cycle) works to clean and recycle the water that is needed by living organisms. They will also learn how surface and ground water are purified by mechanical means for use by people.

SUBJECT MATTER: Environmental Science

LEARNING OBJECTIVES:
Students will be able to:
• Understand the steps of the hydrological cycle
• Identify surface water and groundwater.
• Understand how surface water is cleaned before being used for drinking, bathing, cooking, and other direct purposes.
• Model a process used to clean water by mechanical means that mimics the water cycle.

STANDARDS:
National Science Education Standards
http://bob.nap.edu/html/nses/html
Content Standard B: Properties and changes of properties in matter
Content Standard D: The structure of the earth system, including the water cycle and the role of the sun in providing the energy needed in the water cycle
Content Standard E: Understanding about science and technology
Content Standard F: Populations, resources, and environments and science and technology in society

Louisiana Science Frameworks:
State Standards for Curriculum Development
http:www.doe.state.la.us/doe/assessment/standards/SCIENCE.pdf
SE-M-A7:  Demonstrating knowledge of the natural cycles, such as the carbon cycle, nitrogen cycle, water cycle, and oxygen cycle;
SE-M-A8:  Investigating and analyzing how technology affects the physical, chemical, and biological factors in an ecosystem;
ESS-M-A10:  Explaining (illustrating) how water circulates — on and through the crust, in the oceans, and in the atmosphere — in the water cycle.

MEDIA COMPONENT:
Video:
Enviro-Tacklebox™, Water: From the Earth for You—an LPB Production—explores one of our most precious resources—water and the increasing demand placed on it by communities across the United States.

Web sites:
US Environmental Protection Agency: Drinking Water for Kids: Water Treatment Cycle
http://www.epa.gov/gowdw/kids/treat.html Shows students a model of how water is cleaned for drinking at a municipal treatment facility.
The Water Cycle http://www.suburbanwatersystems.com/kz_thewatercycle.htm Shows students a model of the hydrologic cycle with an explanation of each step in the process
US Environmental Protection Agency: Water Trivia Facts http://www.epa.gov/ogwdw/kids/filter.html
Gives a list of water trivia facts for teachers to test students= knowledge

MATERIALS:
Per Class:
• Poster of the hydrologic cycle (can be downloaded and copied from the site,
http://www.suburbanwatersystems.com/kz_thewatercycle.htm)

Per Group (of 4 students):
• One clear, empty 2 L soda bottle with the cap
• Two clear, empty 2 L soda bottle with the top three inches cut off
• 1000 ml in volume of fine sand
• 1000 ml in volume of coarse sand
• 500 ml in volume of small natural aquarium rocks (washed thoroughly)
• 20 grams of Alum (potassium aluminum sulfate; available in pharmacy or spice aisle in grocery store)
• A large beaker or jar
• 1 coffee filter
• 1 rubber band
• 1 tablespoon
• A clock with a second hand or a stopwatch
• Large plastic basin to catch water spills
• Paper towels
• Data/Observation Sheet (one for each student)

For Culminating Activity:
Per Student:
• A wide-mouth jar
• Plants
• Bottle cap or shell of water
• Soil
• Sand
• Small rocks or medium-sized gravel

PREP FOR TEACHERS:
1. Prior to teaching the lesson, view Water: From the Earth for You.

2. CUE the video to the beginning of the tape.

3. Bookmark the Web Sites used in the lesson for each computer in your classroom or in the computer lab.

4. Prepare copies of the student worksheets (Water Cycle and Data/Observation Sheet.)

5. Prepare "river water" by combining water, grass, and soil in a 2 L bottle for each group, or obtain real river water for use with each group.

6. Gather materials for the Learning Activity and Culminating Activity #1.

7. Obtain a large poster of the water cycle.

8. When using media, provide students with a FOCUS FOR MEDIA INTERACTION, a specific task to complete and/or information to identify during or after viewing of video segments, Web sites or other multimedia elements.

INTRODUCTORY ACTIVITY:
1. Ask students, "From where does the water we use to drink, bathe, wash clothes, and cook with come?" (Students should mention lakes, rivers, ponds, and wells.) Ask, "Does this water come straight from these sources through pipes into our faucets?" (They should respond that the water has to be cleaned first.) Place three glasses of water on the table in front of the students. If possible, one glass should have water from a local river, one from a local pond, and one from a local well. If not available, have at least one glass from a local surface water source. Water from a local surface water source should be cloudy or contain floating debris in it. Ask students, "Is this how the water that comes from our faucets looks? Is this water safe to drink, cook with, or bathe in? Why or why not?" (Students should respond that the water might have contaminants in it.) Tell students that this water came from a local surface water source and name it. Ask, "What might be in water that comes directly from a lake, river, stream, or pond?" (Students should respond that leaves, sediment, algae, fertilizers, oil, gasoline from boats, trash, animal wastes, microorganisms, etc. might be in surface water.) Ask students, "What is done to water so that it is safe enough for people to drink, cook with, or bathe in? What happens to the water after it leaves the surface source and before it comes through our pipes?" Write their responses on the board.

2. Provide students with a FOCUS FOR MEDIA INTERACTION, asking them, "Where do most Americans get their drinking water from and what percentage does each contribute to the drinking water?" PLAY the video, Water from the Earth for You. PAUSE the video when you hear the narrator say, "Presently, 44% of Americans get their drinking water from groundwater sources and about 56% of Americans get their drinking water from surface water sources." Ask students, "What are the two water sources?" (groundwater and surface water.) Ask, "What do you think the differences are between the two of them?" (surface water is rainwater, runoff, or water from water bodies, such as streams, rivers, ponds, or the ocean and groundwater is water that percolates down through and collects under the surface of the soil in underground aquifers.) Ask students, "How much water that is used by Americans comes from groundwater sources (46%) and how much water comes from surface sources?" (54%).

3. Tell students that today they will learn how water from surface sources and groundwater sources is purified so it can be used directly by people.

LEARNING ACTIVITIES:
1. Show students the poster of the hydrological cycle. Ask them if they can explain it to the class. (Allow for student responses.) Tell students that the hydrological cycle is nature's way of purifying water so it can be reused over and over again. Ask students if they know how much of the water that is here today was here when the dinosaurs roamed the earth? Tell them that we have the same amount of water on the earth today as we did in the time of the dinosaurs. Let them know that we are reusing water that the dinosaurs used. Ask students if there were people around to clean the water that long ago. How did the water get cleaned so it could be reused back then?

2. Divide students into groups of 2 to work on the computer(s). Provide students with a FOCUS FOR MEDIA INTERACTION, telling them that they will be learning how the water cycle works to clean water. Provide students with Worksheet 1: The Water Cycle. Have students review the questions they will answer upon finishing their reading. Students will find the answers to the questions at the Web site: http://www.suburbanwatersystems.com/kz_thewatercycle.htm#words Review answers to research questions when all students have completed the activity.

3. Provide students with a FOCUS FOR MEDIA INTERACTION, telling them, "Watch the video to observe how water is cleaned in a municipal treatment plant before people drink it." PLAY the video segment beginning when you see a map showing New Orleans and hear the words, "People in New Orleans, the city near the mouth of the Mississippi River, drink water that comes from the river." PAUSE the video when you see the Mississippi River in front of the city of New Orleans and hear the words: "The city spends about six million dollars a year on water treatment." Ask students whether this is a surface water source or a ground water source (surface water source). Ask students what might be in the water of the Mississippi River that would cause it to need to be cleaned before being drunk (sediment, animal wastes, oil, gas, trash, pollutants, harmful microorganisms, sewage, etc.) Ask students how they think these things are removed from the water so it is safe for drinking. (Accept all reasonable responses.) Resume the video with the next section that shows Reel Places—The New Orleans Water Treatment Facility. Ask students to compare the steps used in water treatment with the water cycle steps they just learned about. PAUSE the video when you see a picture of a glass flask with the word "Water" on it and right after you hear the words, "Water, we love you!" Ask students what steps were used to clean the water at the treatment plant. List their responses on the board. Then ask students which steps in the water cycle are similar to the steps in the water treatment process at the municipal water treatment plant. (As the water is brought in at the intake center, ferric sulfate is added to cause the sediment and other impurities in the water to clump together. As the "floc" gets heavy it sinks to the bottom of the container, allowing the cleaner water to flow into the next compartment. This step is comparable to the evaporation step where the impurities in the water are left behind and only pure water in the form of water vapor escapes into the atmosphere. From there, chlorine is added to begin the disinfection process. Later, ammonia is added to change the chlorine to chloramine. (Chloramine is a weaker disinfectant than chlorine but is more stable and therefore more desirable in water purification.) The water is then filtered to remove any remaining impurities before traveling to the next compartment. This is comparable to the infiltration step of the water cycle where water seeps into the ground, using the soil as a filter and becomes a part of the water table. The final step shows the water being stored in a water storage tank until it can be distributed to people's homes and businesses. This step is comparable to the water that is stored as surface water and ground water in the water cycle.)

This activity is based on the lesson called "The Water Filtration Process" found at the EPA Web site:
http://www.epa.gov/OGWDW/kids/filter.html. Tell students that they will model the process used at a treatment plant to clean some "river water." Be sure to tell them that there are different processes used by different treatment plants and that some steps are left out or done in a different order.

1. Have students pour about 1.5 L of "River Water" into a 2 L bottle. Have students describe the appearance and smell of the water. Ask them if it is clean enough to drink right now.

2. Aeration is the addition of air to water. It allows gases trapped in the water to escape and adds oxygen to the water. Tell students that this step is not used at the New Orleans Water Treatment Facility, but is used at other places. Have a student in each group place the cap on the bottle and shake the water vigorously for 30 seconds. Continue the aeration process by pouring the water into either one of the cut off bottles, then pouring the water back and forth between the cut-off bottles10 times. Ask students to describe any changes they observe. How does the water look? How does it smell? Record observations on the Data/Observation worksheet. Pour the aerated water into a bottle with its top cut off.

3. Coagulation is the process by which dirt and other suspended solid particles are chemically"stuck together" as floc so that they can be removed from the water. Tell students that alum and other chemicals are added to water to form “floc” which attract the dirt particles. The combined weight of the dirt and the alum (floc) become heavy enough to sink to the bottom during sedimentation, leaving the water above it clearer. Tell students to use the tablespoon to add 20 g of alum crystals to the aerated river water. Slowly stir the mixture for 5 minutes, observing what is happening. Ask students to describe the appearance of the water before, during, and after stirring. Record observations on the data/observation sheet.

4. Sedimentation is the process that occurs when gravity pulls the particles of floc (clumps of alum and sediment) to the bottom of the cylinder. Allow the water to stand undisturbed in the cylinder. Ask students to observe the water at 5 minute intervals for a total of 15 minutes and write their observations about how the water's appearance is changing on the data/observation sheet. While students are waiting for the floc to settle, review some water trivia questions with them to test their water knowledge. Questions can be found at the Web site: http://www.epa.gov/ogwdw/kids/filter.html. Set a timer and stop every five minutes to make observations.

5. Have students construct a filter from the second bottle with the bottom cut off as follows:
a. Attach the coffee filter to the outside neck of the bottle with a rubber band. Turn the bottle upside down and pour a layer of pebbles into the bottle.
b. Pour the coarse sand on top of the pebbles.
c. Pour the fine sand on top of the coarse sand.
d. Clean the filter by slowly and carefully pouring 1 L (or more) of clean tap water through the bottle. Try not to disturb the top layer of sand as you pour the water.

6. Filtration through a sand and pebble filter removes most of the impurities remaining in the water after coagulation and sedimentation have taken place. After a large amount of sediment has settled on the bottom of the bottle of "river water," carefully—without disturbing the sediment—pour the top two thirds of the "river water" through the filter. Collect the filtered water in the beaker. Pour the remaining (one-third bottle) of "river water" back into the collection container. Compare the treated and untreated water. Ask students whether treatment has changed the appearance and smell of the water. Record observations on the data/observation sheet.

7. Disinfection is often the last step in the water cleaning process. It is the second step in the process used at the New Orleans Facility. A small amount of chlorine is added or some other disinfection method such as exposing the water to UV lights is used to kill any bacteria or microorganisms that may be in the water. Using an eyedropper, a student in each group should add about 10 drops of "disinfectant" to the treated water. (Due to the caustic nature of disinfectants, substitute distilled water to model the process instead of using chlorine or bleach.) Tell students that just enough disinfectant is used to ensure that all harmful microorganisms are killed. Water usually then goes through a dechlorination step to neutralize the chlorine before being stored for drinking. At the New Orleans Facility, ammonia is added shortly after the chlorine is added to change the chlorine to chloramines, which is less likely to produce carcinogens. The chloramine remains in the water and continues the disinfection process. A residual amount remains in the water while in storage and distribution.

8. Purifying Ground Water: Explain to students that ground water is very much a part of nature's water cycle. Usually, on its travel through the soil layers, the water is cleansed of impurities, making it clean when it is drawn from the ground. Water that comes from underground aquifers usually needs little cleansing before it can be used by people. However, when pollutants leak, spill, or are carelessly discarded onto the ground, they, like water, move slowly or quickly through the soil, depending on the soil, the nature of the pollutant, and the amount of extra help it gets from incoming precipitation. If there is a water supply well near a source of contamination, that well runs the risk of becoming contaminated by polluted ground water. If there is a nearby river or stream, that water body may also become polluted by the ground water. Water that is drawn from ground water sources is usually tested for its purity, and a small amount of chlorine is added to ensure that there are no harmful microorganisms in it, before it is distributed to homes.

Remind students about the Filtration step they just completed and tell them that this is a miniature example of how nature cleans the water that travels through the soil, i.e. groundwater.

CULMINATING ACTIVITIES:
Have students build their own water cycle model by following these steps:
1. Use the materials listed in the Materials List at the beginning of the lesson.

2. Fill the jar first with small rocks, then sand, then soil.

3. Add plants in the soil and place your bottle cap or shell of water in the jar.

4. Put the lid on the jar and place it in a sunny windowsill.

5. Observe the changes that take place in the jar over time. Have students identify the steps of
the water cycle they observe. Ask students, "What happens to the water that is evaporated?
Does it disappear? What happens to the water that falls as precipitation? Does it disappear?
How does the water cycle or move through the mini-ecosystem?"

CROSS-CURRICULAR:
ART:
• Have students draw, color, and label a diagram of the water cycle.
HISTORY:
• Research the history of water treatment and write a report or create a timeline.
LANGUAGE ARTS:
• Write a story about a drop of water as it travels through the water cycle or a water treatment plant using the facts learned in the lesson.
MATHEMATICS:
• Research the amount of water that is used for different tasks such as bathing, brushing teeth, washing dishes, and other tasks. Use the amounts to create word problems involving water usage. Keep track of the amount of water students use for a week at home. Share data with the class and record on graphs.
Science:
• Research how wastewater is treated before it is returned to water sources to be reused. Draw and label a diagram of the process. Have students compare it to the process used to clean surface water.
SOCIAL STUDIES:
• Learn about the different careers available in water treatment. Have representatives of these careers speak to the class or have students write reports on the job qualifications, education required, and job responsibilities.

COMMUNITY EXTENTIONS:
• Find out what water source is used in the city/town where the students live and visit it. Have students write a report to compare how water is cleaned at the local facility and on the video. What steps do they both use? What steps are different? Why?
• Have a water treatment plant operator visit the class and explain the treatment process used there. Prepare a list of questions to ask before the visit.
• Visit a wastewater treatment facility and compare how water is cleaned there as opposed to a source water treatment facility.

STUDENT MATERIALS:
• Worksheet for Water Cycle Research (  PDF )
• Answer key for Water Cycle Worksheet (  PDF )
• Data/Observation Sheet (  PDF )