Week 9 · Chapter 7 Food Chain: 7-1 Food Chain; 7-2 Living Organisms, Air, and Water · 3 lessons
3
Air and water link everything alive
Science P6: Term 1, Chapter 7, pp. 62–67
GoalShow how animals, plants, air and water are linked.
New words
oxygen · the gas that animals breathe incarbon dioxide · the gas that animals breathe out and plants usewater cycle · the movement of water between the ground, air and clouds
Explanation
Living things are linked through air and water. Plants make oxygen in photosynthesis, and animals use it to breathe. Animals breathe out carbon dioxide, and plants use it to make food. So plants and animals depend on each other. Plants also send water vapour into the air by transpiration, and this joins the water cycle. Water goes up into the air, forms clouds and falls again as rain. Imagine what would happen if all plants disappeared: animals that eat plants would have no food, then carnivores would have no food either, and the oxygen in the air would slowly fall. That is why we protect plants and keep our school gardens green.
Worked examples
Karim’s class takes a tally of a school garden: 12 plants, 5 insects, 2 birds. They draw a chain from one plant to an insect to a bird.
Role play: one child is a plant and gives green cards to the animals. If the plant child leaves the game, the animal children cannot get food cards. This shows what happens if plants vanish.
A tree by the road lets water vapour into the air from its leaves. This joins the water cycle; the vapour may become cloud and rain later.
Class activity
What if? With a partner, act out what happens in a food chain when plants disappear. Then write three sentences: one on oxygen, one on carbon dioxide and one on water. Plant a seed or a cutting if you can.
Practice
1
Which gas do plants give to animals?
Oxygen.
2
Which gas do animals give to plants?
Carbon dioxide.
3
How do plants join the water cycle?
They send water vapour into the air through transpiration.
4
If plants vanished, what would happen to the herbivores?
