Lesson 4: Demonstration of Water Pollution

Grade 5-8 (Science and Social studies)
Grade 9-12 (Science and Social studies)

Topic: A closer look at the types of pollution

Time: 60 minutes

Space Requirement: Regular classroom

Methodology: Demonstration, class discussion, cooperative learning

Materials: 1- 1000 mL beaker (large clear container), 3-250 mL beakers (3 clear glasses), vegetable oil (1/2 cup), soil/dirt, food colouring, garbage (coffee grounds, orange peels, paper pieces, metal fragments), Pollutant sheet cut into individual cards (1/student)

Objectives: The students will be able to describe how the three types of water pollution appear on their own and how they look when combined. Students will also be able describe the difficulties facing pollution clean-up.


  1. Prior to the lesson print of the sheet called Pollutants Sheet. Cut the each “pollutant” out. Each student in the class should have one card representing the one pollutant to bring the next day.
  2. Copy the chart below on to the board before the lesson begins.
  3. Review the types of pollution from Lesson 2. (5 min)
    a. The types are hydrocarbons, dissolved substances, solids
  4. Demonstrate these three conditions, each in a separate container. (20 min)
    a. Provide a definition of TDS as Total Dissolved Solids.
    b. Provide a definition of pH as the amount of hydrogen in the water.
    c. Fill each container 1/3 to 1/2 full of water and take a TDS and pH measurement of the clean, local water. Record these numbers on the board in the following chart:
TDS and pH chart

d. add the pollutants (one per container) and take the TDS and pH values again and add to the chart. Please note: You can add the oil to the water to make observations but do not measure the TDS, the oil will cause the meter to no longer work properly.
e. The students should describe what they see (oil floats, dirt settles out, food colouring dissolves).
f. Ask the students how they think the “pollutants” should be removed from the water.
    i. Should get answers like: filter, add bleach, add some other chemicals

5. Pour all three containers into the one larger container and mix together.

6. Have the students describe what they see at the following intervals: initially, after       three minutes, and after five minutes. (15 min)
a. Have one student come up and take a TDS measurement. Have another student take a pH measurement and record the numbers on the board.
b. Ask the students how they would remove the “pollutants” now.
c. To prompt responses ask if the solution could be filtered, have bleach added to it, have other chemicals added to it? Would it be safe to drink it afterwards?

7. Ask the students what they would do if the local stream/river/lake/ocean had water that looked like the water in the container. Could they filter all the water, add bleach to it? (5 min)
a. Have the students suggest alternatives for cleaning the local water body.

8. Hand out the pollutant cards, one per student. Tell the students to bring what they see on their cards to class the next day. (5 min)

9. Remind the students to fill in their water bottle charts.
**DO NOT dump out the large container of dirty water; put it aside for the next lesson

Evaluation: Have each student write out a hypothesis for how the water should be cleaned. The hypotheses are to be handed in at the end of the lesson. Keep the hypotheses and hand back when the filters are being constructed (Lesson 6).

For the Teacher: The goal for this lesson is for students to see some types of water pollution in terms of how they affect water on their own and when combined. The measure of both the TDS and pH allows the tester to see the potential for larger problems and are indicators that a more thorough test must be conducted. The detailed use and information sheets for these two meters are listed in the Related Links section below.

If there is more time, try adding molasses, vinegar and baking soda to the mixture of pollutants and observe the results.

When students are preparing their “pollutants” for the lab, you may have to contact other teachers in the school to gather enough pencil shavings for the students.

Related Links:
TDS and pH General Information

Resources: The “Pollutants Sheet” is below and will require cutting out the individual cards.

Extension Activity: The Safe Drinking Water Foundation has other educational programs that can be taught with this set of lessons. Operation Water Drop looks at what chemical contaminants there are in water and is designed for a science class. Operation Water Flow looks at how water is used and where it comes from and is designed for a Social studies and Math collaboration. Operation Water Spirit presents a First Nations perspective of water and water issues and is designed for a Native Studies class. Operation Water Health looks at common health issues surrounding drinking water in Canada and around the world and is designed for a Health, Science and Social Studies collaboration. To access more information on these and other educational activities visit the Safe Drinking Water Foundation website at www.safewater.org.

Pollutants Sheet

Pollutants oil coffee grounds peel from carrot banana peel orange peel