the water and linking those activities to various pollutants. Ask students to listen for the word(s) printed on their canister as you tell the story. When they hear it, they are to come up to the tank, open the canister and pour its contents into the “river” (the aquarium). For example, in my class in


Yuck! We did this to our river?


Label on canister Trees


Pollutant in canister dry leaves (organic material)


Building construction dry soil (eroded soil) Farmers


Barnyards Septic tanks Coal mine


Electric power plant Hydroelectric dam Commuters


Gardeners Antifreeze


Washing the car


Expired medication Mystery liquid Motorboats Picnicking Fisherman Wastewater


Procedure:


1. Place the aquarium, half full of clear water, at the front of the classroom. Provide each student with a labelled canister containing one of the substances representing water contaminants. Instruct the students not to open their canisters yet, but to read and remember the word(s) on the label.


2. Begin telling the story of your local water source, briefly recounting human activities and development on or near


baking soda (fertilizer) water and instant coffee (leachate)


water, yellow food colouring, toilet paper (human waste)


vinegar (acid) vinegar (acid)


silver cake sprinkles (mercury)


vegetable oil and vinegar (motor oil and particulates)


baking soda (fertilizer)


water and blue food colouring water and dish soap jellybeans (pills)


water and red food colouring (poison) vegetable oil (motor oil)


candy wrappers, pop cans (litter) dental floss (fishing line) raisins (human waste)


Winnipeg, Manitoba, we recount the history of the Red River, which flows through the city (see “Who Polluted the Red River?”). I ask students how the first humans to live in the area might have used the river, and we talk about how clean the water likely was at that time. We then continue our story: As settlers arrive, building construction causes soil to erode into the river. At this point, the student who has the film canister labelled “Building construction” comes to the front, opens the canister and pours


clay soil into the aquarium. As the story progresses and the aquarium water becomes more and more polluted, the students are horrified!


3. When all of the canisters have been emptied into the aquarium, invite the students to look at the “river” up close. At this point, I ask students, “Who did pollute the Red River?” Of course, they realize that we have all played a part in its contamination.


4. Follow the demonstration with a discussion of sustain- ability. Explain that there are three main impacts to be considered when we talk about the sustainability of an activity: its impact on the environment, on the economy, and on human health and well being. Guide students to think about the impacts of some of the activities and practices that pollute water sources. For the environ- mental impact, the answer is easy: contamination of the water source. Students will also readily grasp how human health and well-being are affected: that we need clean drinking water to survive, and we want our rivers and lakes to be clean for swimming, fishing and other purposes. It may be more difficult for students to make the link to economics. A discussion that leads to the cost of water treatment facilities in the local community will demonstrate that there is an economic cost to cleaning the water after we have polluted it.


5. Finally, challenge students to think about what can be done differently in their own lives at home and at school. Students may come up with many ideas, such as not flush- ing objects down the toilet, returning expired medications to the pharmacy for safe disposal, picking up pet wastes, and using compost rather than chemical fertilizers on gardens. Following this discussion, point out that while the class has come up with many good suggestions for preventing water pollution, there still remains a question: What do we do with the polluted water in our “river” (the aquarium)? This is where the second activity comes in.


GREEN TEACHER 83 Page 29


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