Pre-Visit Activities : Water Quality : Procedures Sixth - Eighth Grade Online Curriculum : Watersheds

Materials

Part 1
Mini-lab 1

• pH paper
• water
• lemon juice
• vinegar
• soda
• milk
• baking soda
• bleach
• shampoo
• orange juice
• detergent
• cups or beakers
• safety goggles

Mini-lab 2

• glass beakers
• salt
• water
• pH paper
• hydrometer/refractometer
• thermometer
• dissolved oxygen kit or meter
• hot plate
• safety goggles

Part II

• pH paper
• hydrometer or refractometer
• thermometer
• dissolved oxygen kit

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Procedure

Part 1

Discuss water quality with your students. Ask them what they think water quality is. Teachers may want to use two photographs, one of a polluted stream and one of a healthy stream. Have students discuss factors that influence water quality. In the discussion focus on temperature, pH, dissolved oxygen and salinity as some of the factors that can be measured to determine water quality.

Mini-lab 1

1. Ask students if they’ve heard of pH. Introduce the terms acid, base and neutral. Discuss the pH scale.
2. Have students determine the pH of five household products. You may choose to use water, soda, vinegar, lemon juice, shampoo, milk, bleach, orange juice, detergent, baking soda or any other product that would be acidic or basic. (Mix baking soda and water to create a solution.)
3. Each group of students should be given five beakers containing the household products listed above. They should determine the pH of each item. Have them record their data in their journal. They should determine if each substance is an acid or base. Remind students to wear safety goggles.

Mini-Lab 2

1. Discuss salinity. Ask students what salinity is, what bodies of water should have greater salinity and where the salt comes from.
2. Have students measure the salinity of two water samples. To create these samples, add salt to a beaker of water. Mix well. To the second beaker add only water. Have students determine the salinity using a hydrometer or refractometer. These tools can be ordered from a scientific supply company. Students should also measure the temperature, dissolved oxygen and pH of each sample.
3. Next, heat the water samples using a hot plate. Allow evaporation to take place. After the sample has cooled, have students measure the salinity, temperature, dissolved oxygen and pH again. Record results and discuss why changes may have occurred.

Part II
Using information learned during the mini-labs, have students design an experiment to determine the water quality of a local body of water. They may use a drainage ditch, stream, river, pond, etc. Students should include temperature, pH, salinity, and dissolved oxygen. Other factors such as turbidity and stream velocity may also be included.