Week 27 · Unit 4: Concept 4.2 (C): habitat destruction, water pollution, building with soil, unit project Environmentally Friendly Cities · 3 lessons
2
Cleaner water, healthier life
Science P6: Term 2, Unit 4, pp. 72–79
GoalExplain why preventing water pollution is better than cleaning it up and list simple ways to prevent it.
New words
pollution · harmful materials in air, water or soilsewage · used water and waste from homesfertilizer · a substance added to soil to help plants grow
Explanation
More people and more factories mean more used water and more chances for pollution. Cleaning polluted water takes a lot of time, work and money, so preventing pollution is better. Sewage from homes and used water from factories must be treated before they go back to rivers or the sea. Farmers can use only the right amount of fertilizer; too much washes into streams and harms the water. Keeping natural plants along rivers and canals helps because roots and leaves trap soil and waste. Putting rubbish in its place, not in the water, stops plastic and other waste from drifting away. Clean air also protects water, because dirty air can fall into water with rain. Each of these steps helps fish, plants and the people who depend on the same water.
fertilizer, rubbish or waste enters water→plants, fish and people are harmed→prevention keeps the water clean
Worked examples
A factory has a tank that cleans its used water before it flows to the river. This is treatment, a way to prevent pollution.
Action
Helps because
treat sewage
harmful waste is removed
use the right amount of fertilizer
less washes into water
bin the rubbish
less waste in water
A farmer puts a handful of fertilizer on each plant, not a bucketful. Using the correct amount keeps extra fertilizer from washing into the canal.
Mina says cleaning up is just as good as prevention. Cleaning is possible but slow and costly, and some damage may already be done.
Class activity
Schoolyard clean-up. With a grown-up, wear gloves and collect rubbish from a small part of the yard into bags. Sort it into paper, plastic, metal and food. Never touch sharp things or broken glass. Count each pile and make a bar chart. Wash your hands.
Practice
1
Why is preventing pollution better than cleaning up?
Cleaning takes more time, work and money, and harm may already be done.
2
Name two ways to keep water clean.
For example treat sewage, use the right amount of fertilizer, keep plants, bin rubbish.
