Seeing Water Pollution

Goal 14: Life Below Water


A simple exercise that shows how pollutants act in water, and how non-solid pollutants can be particularly damaging to life below water, and ecosystems in general.


stopwatch45-minute lesson + homework assignment

circular-line-with-word-age-in-the-center13 – 16 years old

group-of-three-men-standing-side-by-side-hugging-each-otherGroups of up to 25


Behavioural competences

To take personal and local actions to reduce water pollution
To take personal actions to influence local politics


To reflect upon how each one of us pollute the water and the consequences of this
To reflect upon global effects of local water pollution and vice versa
To reflect upon how one can influence local policies on water protections

Lifelong learning key competences

Basic competences in science and technology
Social and civic competencies


Coffee filters or other filter paper
A number of glass/clear plastic containers:

  • 2 large containers (2l+)
  • 4 to 6 small containers (150ml)

Water samples

  • Clear tap water
  • Tap water ‘polluted’ with food colouring
  • Tap water ‘polluted’ with washing liquid/shampoo
  • Tap water ‘polluted’ with bits of plastic
  • Tap water ‘polluted’ with an eraser/rubber grated into small pieces
  • Tap water ‘polluted’ with any other ideas you have

Toy fish/something to represent life under water

The following materials could be used to present the exercise in plenary in front of the whole class, alternatively, if you wish the students to have a practical exercise, you could provide a set of the materials to each group


Fill the largest glass container with clear tap water (leaving space to add more liquid), place inside the toy fish/something to represent life, explain to the class that this represents a river/the sea.

Explain that the fish depends upon its surroundings for life, and that the fish is part of a delicate ecosystem and food change, that includes us.

Choose one of the small contaminated water samples, and pour it into the river/sea, explaining that it represents direct pollution, or in-direct pollution, i.e. another source of water that is polluted is joining the river/entering the sea.

Let the pollutant settle into the river/sea, ask the students

  • To observe how the pollutant is reacting/effecting the clean water (is it floating, sinking, sitting on the surface, totally dissolved into the water?)
  • To observe how the pollutant might be effecting the life of the fish, and other life that is dependent upon the life of the fish.

Continue the same process with the other polluted samples.

Stir the water to mix the pollutants fully within the clean water and leave it to settle, explain that the stirring represents the current of the river/the tide of the sea.

Ask the students to further comment upon how the pollutants are acting within the water, and how it could impact the life of the fish, and the ecosystem. Ask the students to comment upon how the different pollutants act differently in water and effect the life differently.

Use the filter paper to filter the water into a new container.

Ask the students to examine what was left behind in the filter, explain that this represents how the pollutants could be washed up on beaches/river banks.

Ask the students what impact this could have.

Ask the students to comment upon the filtered water, is it still polluted or is it clean again? Ask the students to expand upon this, what does it imply?

Take a sample of the polluted water that has been filtered and pour it into a fresh container of clear water, explain to the students that this represents the river/sea, entering another river/sea a long way away, and therefore further polluting further rivers/oceans).

Ask them to comment on this.

End the session by presenting to the students their homework assignment (evaluation/reflection)


Homework task – Ask the students to think about the lesson, and to write a letter addressed to their Mayor, explaining why they think it is important that we reduce water pollution, and what impact water pollution is having on life underwater and our world.

Follow up suggestions

Collecting and analysing Articles on water pollution – you could have a further lesson why you ask the students to read articles upon water pollution locally and around the world (the students could be given the task of collecting the articles as homework, or you could collect them yourself).

You could ask the students to make a ‘chain of consequence’ of the situation described in the article, or develop a strategy for a solution/to have avoided to the situation.