Water Quality
by Leslie Schaffel
Lesson I - Cleaning Water
Introduction: This would be a good introductory activity to use prior tovisiting a sewage treatment or water filtration plant. Prior to doing thisactivity, discuss these types of pollutants: chemical, sewage, trash, nuclear,soil. Discuss methods of cleaning water.
Time: one to two 50 minute class periods; best suited for groups of 3-4.
Materials:
-3 clean flower pots of the same size (the kind with one center drain holdand no saucer)
-driveway gravel
-aquarium gravel
-cheesecloth
-water
-soil which has some small roots, leaves, twigs or other debris mixed inwith it
-clean bucket or dishpan
Procedures:
1. Label the glass jars: #1 = driveway gravel; #2 = aquarium gravel; and#3 = cheesecloth
2. Fill the first pot with driveway gravel. Fill the second pot with aquariumgravel. Line the third pot with three layers of cheesecloth. Make the cheeseclothcome up over the lip of the pot.
3. Fill each of the glass jars full of water.
4. Stir the soil to mix the debris evenly; then pour cup of soil into eachof the glass jars. Stir to mix it well.
5. Hold the flower pot with the driveway gravel over the bucket or dishpan.Pour the contents of jar #1 through the gravel and catch it in the bucket.Wash the jar and pour the water from the bucket into it. What color is thewater? How much debris is in it? Wash the bucket or pan before startingthe next step.
6. Hold the flower pot with the aquarium gravel over the bucket or dishpan.Pour the contents of jar #2 through the gravel and catch it in the bucket.Wash the jar and pour the water from the bucket into it. What color is thewater? How much debris is in it?
7. Hold the flower pot with the cheesecloth over the bucket or dishpan.Pour the contents of jar #3 through the gravel and catch it in the bucket.Wash the jar and pour the water from the bucket into it. What color is thewater? How much debris is in it? Would you want to drink the water fromeither of these jars?
Conclusion: The water running through the driveway gravel should be freeof large debris but muddy. The water running through the aquarium gravelshould be less muddy and free of large debris. The water running throughthe cheesecloth should be less muddy than the other containers and freeof large debris.
Lesson II - Take a Dip
Introduction: Water has varying effects on different substances. It maybe extremely damaging or have no effect at all. The consistency of the object,the water temperature, movement or stillness of the water, and content ofthe water are factors that must be considered. In this activity, studentswill observe the effects water has on objects. Various objects are observedboth before and after being placed in water.
Time: Two 50 minute class periods will allow for testing and discussion,divide class into groups of 2-4 each
Materials:
-Per group: items to be tested (3 samples of each, with one serving as acontrol): sugar cubes, salt, crackers, soil, chalk, iced tea mix, buttons,paper towels, dried soup, flour, and so on
-magnifying glass
-a jar and plastic cup for each of the tested samples, warm and cold
Procedures:
1. What happens to various objects when placed in water?
2. Have the students observe and list the characteristics of each of thesamples to be tested. Have them use magnifying glasses to double check theirobservations and discuss the findings.
3. Have the students place the items to be tested in jars of cold waterand observe the results. Have them list the changes observed and recordthe time needed for items to change.
4. Discuss the results. Have the students describe each substance and thechanges observed after one to two minutes.
5. Is there anything that can be done to the water that may change the resultsfor a particular item? Have students predict results for each change (stirringthe water, warming the water, adding salt, and so on).
6. Have the students test each object in warm water and discuss the results.
7. Have the students compare results for warm water versus those obtainedin cold water. Did the objects change faster or more slowly?
8. Ask students to brainstorm a list of items that are changed as a resultof being immersed in water and list those that do not change. Have studentsbring in various items for testing. Provide opportunities for students tochart their results.
Conclusion:
Water may or may not have an effect on items placed in it. Sometimes boththe water and the item change noticeably, sometimes only the item changes,and sometimes neither changes. Warm water speeds up changes, whereas coldwater tends to slow down any changes.
Lesson III - Pass the Salt
Introduction:
The Earth is covered by various types of water. These types have many differences.Salt water is less transparent, has a stronger smell, is denser, and impedesthe dissolving rate of many materials in comparison to fresh water. In thisproject some of the characteristics of salt water and fresh water are explored.Students test the buoyancy and dissolving rates of various objects whenplaced in both kinds of water.
Time: one 50 minute period is needed; designed for groups of 3-4 students
Materials:
-Per group: 2 tall glasses of jars
-water
-2 teaspoons of salt
-a stirrer
-a magnifying glass
-2 sugar cubes
-2 pieces of hard candy
-other objected to be tested (such as noodle, small pieces of carrot, rice)
Procedures:
1. Have groups fill 2 tall glasses with 10 to 20 centimeters of water. Theyshould place 2 spoonfuls of salt in one of the glasses and stir until dissolved.
2. Have the students observe, list and discuss the characteristics of thecontents of both glasses. (For example, salt water - cloudy, appears thicker,smells; plain water - clear, contains tiny bubbles)
3. Have students place a pair of objects to be tested (such as noodles,rice) in the 2 glasses simultaneously and record observations (a watch orclock with a second hand may be used to record sinking, floating or dissolvingrates). Have students remove the objects from both glasses before testinganother pair. Did the object sink or float? Did the two objects sink atthe same speed? Did the objects react differently in the two liquids? Whydo you think the objects behaved the way they did?
4. Now place a sugar cube in each glass and observe what happens. In whichglass did the sugar dissolve the fastest? Did they dissolve differently?
5. Place a small piece of hard candy in each glass and compare dissolvingrates again. Describe what happened.
Conclusion:
Certain materials are more buoyant in salt water than plain water becauseof the higher density of salt water. The density of salt water also impedesthe dissolving rate of many materials.
Lesson IV - Wetland Model
Introduction: Wetlands help filter silt and pollutants from water, helpprevent soil erosion, and often reduce flood damage.
Time: one or two 50 minute periods are needed; groups of 3 or 4 would workbest
Materials:
-Per group:
-roasting pan
-modeling clay
-sponges
-carpet squares
-pine needles
-twigs
-grass
-weeds
-soil and other natural materials
-cotton swabs
-toothpicks
-plastic toy animals
-markers
-pictures of wetlands and wetland plants and animals
-jar of muddy water
-water
Procedure:
1. Ask the kids to list characteristics of a wetland. Share pictures ofdifferent types of wetlands, including freshwater and salt marshes freshwaterswamps and bogs. Discuss the animals and plants that might live in eachkind of wetland.
2. Explain to the class the steps to making their wetland activity. First,they will spread a layer of modeling clay in half of the roasting pan torepresent land. Leave the other half of the pan empty to represent a lakeor other body of water, such as a river or ocean. Shape the clay so thatit gradually slopes down to the body of water.
3. Smooth the clay along the sides of the pan to seal the edges. You canalso form meandering streams in the clay that lead into the body of water.
4. Place a sponge or carpeting sample that will completely fill the spaceacross the pan along the edge of the clay. The carpeting represents thewetland buffer between dry land and open water. Place model animals andplants onto wetland surface.
5. Pour some water slowly on the land. Have the animals describe what happens.
6. After pouring that water out, do the same procedure with the muddy water.Discuss your results.
Conclusion: By building a simplified wetland model, you can demonstratesome important wetland features. The students should notice that when theypoured the dirty water, the soil particles are trapped by the carpeting,making the water in the body of water much clearer.
Lesson V - Water Pollution
Introduction: This experiment will show you how pollutants get into thesoil and into the water supply.
Time: one 50 minute period; best suited for groups of 3 or 4
Materials:
-Per group:
-a large, flat pan
-soil
-blue or green food coloring
-water
-mister or empty non-aerosol spray bottle
Procedures:
1. Fill the pan with water to a depth of inch.
2. Make a small island of soil in the center of the pan.
3. With your finger, make a small depression or hole in the center of thesoil "island". Fill the hole with food coloring. What happensto the food coloring? What happens to the soil?
4. Fill the mister and spray the island. What happens?
Conclusion: Discuss what the students observed. They should find that thefood coloring mixes with or spreads into the soil. The surrounding soilshould turn the color of the dye. Also, the water should carry the dye downto the bottom of the pan. The water should become colored with the dye.You can also discuss what will happen to toxic chemicals that are dumpedon or in the ground and how we could prevent pollution of our soil and waterfrom chemicals.