Introduction
The water that is available to us to use is not always clean. When water becomes dirty we say it is polluted or contaminated. Water becomes polluted when unwanted materials are added to it. The unwanted materials are called pollutants.
Ways we pollute water: dumping garbage near water sources, putting chemicals like insecticides, fertilizers and factory wastes in our water, oil leaks from ships.
Ways we purify water: treating the water with chemicals called chlorine, boiling, filtering.
Care should be taken at all times to ensure a clean water supply as diseases can be transmitted using contaminated water. Diseases caused by contaminated water are called water-borne diseases. Some of these diseases are cholera, dysentery, typhoid and poliomyelitis.
Task
Identify and describe the ways water can be made safe for drinking.
Process
- Student will be asked to give one word for water that is not safe for drinking. They will be led by clues to come up with the word pollution. Next they will formulate a definition for water pollution.
- They will list and explain how human actions assist in the pollution of water. They will view some pictures showing how water becomes polluted.
https://youtu.be/93BqLewm3bA
- Students will read information provided by teacher and make list of ways water can be purified. They should differentiate purification of small amounts and large amounts.
Evaluation
In groups, students will design and draw simple diagrams to depict water purification and research the consequences of consuming contaminated water.
One group will draw pictures to show the purification methods of water - boiling, filtering and chlorinating.
Next group will carry out a research to answer the question, what happens when we consume or drink contaminated water. They will list at least four waterborne diseases and the symptoms for each.