The Basics: Introduction to Water Quality

Engagement: Set out several samples of water. One should be tap water, one a bottled water, one should smell different, and one should be an odd color. Ask students if they would drink any of these waters? Ask students why they wouldn’t drink the waters and record results on board. Ask what a weird smell or color could tell about the water. Ask students: If water is clear and doesn’t smell, is it safe to drink? Ask students: would they swim in the water? Is drinking water different from water you swim in? Students might point out that you can swim in salt water but not drink it. Ask students about the animals that live in bodies of water such as lakes and rivers. What do they need to survive? What factors are important for them?

Exploration: Students will watch and discuss the powerpoint slides from “Water Quality Overview”. They should use the accompanying sheet to take notes.
Then, divide students into lab groups and make sure that lab safety has been adequately discussed. Each group will rotate around the classroom, conducting water quality tests at each station. Depending on the types of kits you are using, some test kits will take longer than others (for instance, dissolved oxygen, phosphate, and nitrate HACH kits take at least 10 minutes each). Make sure that students have something to do (or read) if they finish with their test kit early. A good alternative is to have microscopes set up with slides of pond water, so that students can observe any plankton in the water. Students should perform the water quality tests according to the directions enclosed in each kit and record their results on notebook paper. This preparation activity will allow you to take your students outside with the confidence that they can perform the tests safely and accurately.

Explanation: Depending on which variables you want to test, the background readings should provide enough information for you and the students. The following parameters are discussed:

• pH
• Dissolved Oxygen
• Phosphate
• Nitrate-nitrogen
• Chloride
• Macroinvertebrates
• Turbidity
• Conductivity
   

Extension: Ask if any students have had a fish tank? If so, discuss the different issues that arise when taking care of a fish tank. What is the filter for? What are the bubbles? What tests do you have to do on the water?

Evaluation: Have students compare table with a partner, and then go over as a whole class. For homework, students should read the background reading entitled “Pollution”.