CLASS 6 SCIENCE · CHAPTER 11 · STUDY NOTES
Nature’s Treasures
Trace everyday needs to natural resources, understand their limits and plan sensible conservation.
01 / EXPLORE & UNDERSTAND
Nature supplies more than things we can hold
Air, water, sunlight, soil and living things support our lives.
1. Trace a familiar object back to nature
A wooden desk is made by people, but its wood came from a tree. A metal bicycle uses metals obtained from minerals. Human-made resources depend on materials and energy from nature.
2. Include what is used indirectly
Breakfast uses crops, water and soil even if you see only food on your plate. Washing a shirt uses water directly; making the shirt also used resources. Looking at both helps us understand why waste matters.
Your turn
Question
Is a solar panel a natural resource just because it uses sunlight?
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02 / EXPLORE & UNDERSTAND
Air is a mixture, not only oxygen
Oxygen supports our respiration, but nitrogen makes up most of the air.
100 equal parts of dry air
- 78%
- Nitrogen
- 21%
- Oxygen
- 1%
- Other gases together
1. Read the hundred-part picture
For a simple picture of dry air, imagine 100 equal parts: about 78 are nitrogen, 21 oxygen and 1 other gases together. The last part includes argon and carbon dioxide; it is not 1% carbon dioxide alone.
2. Remember that water vapour varies
Air can also contain water vapour in changing amounts. The rounded dry-air picture does not show this changing moisture. Air is usually invisible, but rustling leaves or a moving curtain can show its effects.
Your turn
Question
A learner colours 78 squares as oxygen and 21 as nitrogen. What needs correcting?
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03 / EXPLORE & UNDERSTAND
Moving air can do work
Wind is moving air. Its motion can turn blades.
Blades capture moving-air energy
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1. Connect the pinwheel and the turbine
Air pushes a pinwheel’s folded blades and it turns. A wind turbine also has blades turned by wind. A generator connected to the turning mechanism produces electricity; spinning blades alone are not electricity.
2. Match the machine to its job
Wind-driven machines can pump water or grind grain as well as generate electricity. Wind strength varies, so output is not constant. A wind farm has many turbines in a suitable area.
Your turn
Question
Why might a wind turbine produce less electricity on a very calm day?
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04 / EXPLORE & UNDERSTAND
Plenty of ocean water does not mean plenty to drink
We need suitable water, in a usable place and condition—not simply water somewhere on Earth.
1. Separate amount from access
Most Earth water is in salty oceans. Much fresh water is frozen or underground and may be hard to access. Rivers, lakes and wells supply water in many places, but availability differs by place and season.
2. Protect quality as well as quantity
Water supports drinking, cooking, washing, farming and industry. Sewage, waste chemicals and rubbish can pollute sources. Clear-looking water can still be unsafe. Preventing pollution helps keep limited sources usable.
Your turn
Question
Why is “our village has a lake” not enough to prove everyone has safe drinking water?
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05 / EXPLORE & UNDERSTAND
Save water before it is lost or polluted
Small changes at taps and larger rainwater systems can work together.
Trace the rainwater route
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A real stepwell: Toorji ka Jhalra
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1. Follow the roof-to-storage route
Rain falls on a roof, drains into channels and is guided towards a storage or recharge system. Leaves and dirt need to be kept out through a suitable maintained system. Collected rainwater is not automatically drinking water.
2. Combine collection with careful use
Report leaks, turn taps off when not needed and use only the water a task needs. Traditional stepwells store water and can receive seepage from the surroundings. The book shows Toorji ka Jhalra in Jodhpur; learn how your own local system works rather than assuming every well is identical.
Your turn
Question
A school installs rainwater storage but leaves leaking taps unrepaired. What is missing from its plan?
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06 / EXPLORE & UNDERSTAND
Trace food energy back to sunlight
A cow gets food energy by eating grass—not simply by standing in sunshine.
1. Follow this particular pathway
Sunlight → grass makes food → cow eats grass. The Sun is the main starting energy source for this food pathway. The arrows show energy being passed through food, not sunlight travelling unchanged through the cow.
2. Separate food making from warmth
Sunlight can also warm the ground and help water evaporate from wet clothes or drying food. Those are different effects from plants making food. The Sun supports most food chains and many familiar processes on Earth.
Your turn
Question
A cow rests in the shade after eating grass. Has its food energy stopped being connected to the Sun?
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07 / EXPLORE & UNDERSTAND
A solar heater and a solar panel do different jobs
Using sunlight for heat is different from turning sunlight into electricity.
Two ways to use solar energy
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1. Name the useful output
A solar cooker uses sunlight to heat food. A solar water heater warms water. A photovoltaic solar panel converts light into electricity. The devices can look similar from far away, so ask what output each is designed to provide.
2. Plan for changing sunlight
Solar output varies with the sunlight reaching the device. A panel does not generate solar electricity at night. Storage or another supply may be needed. Clouds can reduce output; they do not always make it exactly zero.
Your turn
Question
Why should we not describe a solar water heater as necessarily producing electricity?
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08 / EXPLORE & UNDERSTAND
A forest is a living community
A forest includes many plants, animals, tiny organisms and their surroundings.
Look beyond the tree trunks
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1. Connect food, shelter and soil
Trees and other plants provide food and shelter. Roots help hold soil; fallen leaves decay and return nutrients. Animals can help spread seeds. Removing a large area of trees changes more than the number of trunks.
2. Protect old forests and care for new plants
Planting saplings is useful, but a mature forest’s habitats and relationships take time to recover. The Chipko movement in the Himalayan region involved people protecting trees from felling, including strong participation by local women. Conservation needs ongoing care, not only a planting-day photo.
Your turn
Question
Why do ten newly planted saplings not instantly replace the habitat of ten old trees?
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09 / EXPLORE & UNDERSTAND
Soil is more than powdered rock
Soil contains mineral particles, decayed material, water, air and living organisms.
1. Notice spaces as well as particles
Air and water occupy spaces between soil particles. Roots need space to grow and air for respiration. Earthworms and other organisms can mix and loosen soil. Different samples can differ in colour, texture and contents.
2. Formation is slow; loss can be fast
Weather and living organisms slowly break down rock; decaying remains add organic material. Soil can take a very long time to develop. Roots and ground cover reduce washing away by rain. Protecting topsoil is easier than quickly replacing what has been lost.
Your turn
Question
Why might bare ground lose more soil in heavy rain than nearby covered ground?
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10 / EXPLORE & UNDERSTAND
Rocks and minerals become useful materials
The buildings and devices around us connect to rocks and minerals.
Same broad resource, different uses
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1. Match properties to uses
Slate can split into sheets used for roofing. Laterite blocks can be used in buildings. Granite, sandstone and marble have construction uses. People have also shaped stone into tools for thousands of years.
2. A device has a material history
Metals such as iron and copper are obtained from suitable mineral deposits. Mining and processing use land, water and energy. Repairing, reusing and properly recycling products can reduce demand for new material; minerals are not quickly replaced on a human timescale.
Your turn
Question
How can repairing a metal bicycle help conserve a natural resource?
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11 / EXPLORE & UNDERSTAND
Fossil fuels take far longer to form than to use
Coal, petroleum and natural gas store energy from ancient living material.
1. Separate the source from products
Petrol, diesel and kerosene are obtained from petroleum. CNG means compressed natural gas. Coal can fuel electricity generation. These fuels form over millions of years, so using them today does not make new supplies appear tomorrow.
2. Less pollution is not no pollution
Burning fossil fuels releases carbon dioxide and can release other pollutants. Natural gas can burn more cleanly than some other fuels, but it is still fossil fuel. An electric vehicle has no exhaust from burning fuel in its motor; the electricity and battery still have a resource history.
Your turn
Question
Does calling natural gas “cleaner” make it renewable? Explain.
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12 / EXPLORE & UNDERSTAND
Renewable does not mean unlimited
Ask how quickly a resource can be replaced and how quickly we are using or damaging it.
1. Compare replacement rates
Water circulates through natural processes and forests can regrow. Yet overuse or pollution can make local water scarce, and cutting faster than regrowth can destroy a forest. Fossil fuels, minerals and slowly formed soil cannot simply be replaced next season.
2. Turn understanding into a practical plan
Choose a local problem: a leaking tap, wasted paper or damaged saplings. Record it, ask the responsible adult for a repair or care plan, and check the result later. Conservation combines reduced waste, reuse, protection and fair access—not simply telling others to use nothing.
Your turn
Question
A forest is cut down faster than new trees mature. Why is “trees are renewable” an incomplete defence?
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Take these ideas with you
- Human-made things use materials and energy from nature.
- Dry air is about 78% nitrogen, 21% oxygen and 1% other gases.
- Water access and quality matter as well as total quantity.
- Sunlight supports food pathways, heating and solar electricity.
- Forests protect habitats and soil; recovery takes time.
- Renewable resources still need protection from overuse and pollution.
Use your understanding in a new situation
Question
A family buys a new device every year and recycles the old one. What could reduce resource use further?
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A school counts 12 dripping taps and repairs 9. What should it record next to judge the plan?
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Sign inNew here? Sign up freeNCERT · Chapter source PDF, pages 17, 18, 19, 20, 21, 22, 23, 24 · Original Learnijoy explanations and practice.