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Nature’s Treasures – Class 6 Science Chapter 11 Notes & NCERT PDF

Class 6ScienceChapter 11NCERT book: Curiosity - Science Class 6

Notes and a simple summary of Chapter 11 of the NCERT Class 6 Science book, with the official chapter PDF, flashcards, an MCQ quiz and an AI tutor for your doubts.

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Chapter 11: Nature’s Treasures

Introduction

During school vacations, Bhoomi and Surya visit their Ajji (grandmother) in a village on the edge of a forest in the Western Ghats. The air is fresh, the soil is fertile, there is plenty of sunlight, and trees give food and shelter to birds and insects. Ajji calls these the treasures of nature — without them, life on Earth is not possible. We are all a part of nature.

Key Concepts

11.1 Air

  • In Activity 11.1, holding your breath shows how hard it is to go without air. Our body needs oxygen to perform its functions; we can survive without food or water for days, but not without oxygen for even a few minutes.
  • Air is a mixture of gases:
    • Nitrogen 78%, Oxygen 21%, Argon, carbon dioxide and other gases 1%.
  • Moving air is called wind — fast in a storm, gentle as a breeze.
  • Activity 11.2 – making a firki (paper pinwheel): the wind makes it rotate. A windmill works the same way and can run flour mills, lift water from wells or generate electricity. Wind farms: Muppandal (Tamil Nadu), Jaisalmer Wind Park (Rajasthan), Brahmanvel (Maharashtra).

    • 11.2 Water

  • Used for drinking, cooking, bathing, washing, growing crops and in industries.
  • Water covers about two-thirds of Earth's surface, but most is saline seawater. Freshwater is in ice sheets/snow, rivers, lakes and underground; only a small fraction (ponds, rivers, lakes, wells) is easily accessible.
  • Activity 11.3 – list how water is wasted in daily tasks (hand washing, brushing, bathing, gardening) and ways to reduce it: turn off taps, fix leaks, recycle and harvest water.
  • Trash, household and industrial waste pollute freshwater; polluted water is unfit for living beings. In many places people walk long distances for water — access is not equal.
  • Rainwater harvesting – collecting and storing rainwater for later use; an age-old Indian practice. Stepwells — Bawadi in Rajasthan (e.g., Toorji ka Jhalra, Jodhpur) and Vav in Gujarat — store rainwater and water seeping from nearby lakes and rivers.
  • World Water Day: 22 March.

    • 11.3 Energy from the Sun

  • Ajji dries chillies (and raw mangoes) using the Sun's heat.
    • The Sun is the main source of energy on Earth.
  • The cow grazing grass debate: the cow gets energy from grass, and grass needs sunlight to make food — so the energy ultimately comes from the Sun, not from simply standing in sunlight.
  • Uses: plants make food, drying clothes, solar panels (electricity), solar cooker, solar water heater.

    • 11.4 Forests

    Forests are large areas with a dense growth of various types of plants.
  • Home, food and shelter for wild animals, birds and insects; they give us many products.
  • Ajji's village tradition: collect only fallen nellikai (Indian gooseberry); fruits on trees are left for animals and birds.
  • Forest cover is falling due to large-scale cutting of trees; regrowing a forest takes many years.
  • Van Mahotsav – a week-long forest festival in July.
  • Chipko movement (early 1970s, Uttarakhand) – local women hugged trees to stop them from being felled.
  • Roots hold the soil; fallen leaves decay and enrich the soil — recycling in nature.

    • 11.5 Soil, Rocks and Minerals

  • Spaces between soil particles give air and room for roots; earthworms turn and loosen soil naturally.
  • Activity 11.4 – soil samples from different places differ in colour and texture; they contain sand, insects, worms and tiny organisms; decaying plants and animals become part of soil.
    • Soil is formed by the disintegration of rocks by the Sun, water and living organisms over thousands of years.
  • Rocks are used for houses, temples, roads, dams, table tops; slate for roofing, laterite as bricks; granite, sandstone and marble are important rocks. Early humans made hand axes and arrowheads from stone.
  • Rocks are made of minerals. Metals like aluminium, gold, copper and iron come from minerals, used in airplanes, cars, jewellery, cosmetics and electronics — a basic mobile phone has about a dozen minerals (gold, silver, copper, cobalt).

    • 11.6 Fossil Fuels

  • Activity 11.5 – a survey of vehicles and fuels: petrol and diesel are most common.
  • Petrol, diesel and kerosene come from petroleum. Petroleum, natural gas and coal are fossil fuels, formed over millions of years from buried remains of microorganisms and plants.
  • CNG is a cleaner fuel than petrol or diesel; coal is mainly used to make electricity; LPG and natural gas have replaced wood, coal and dung cakes in kitchens.
  • Fossil fuels are limited and their burning releases smoke and carbon dioxide, causing air pollution. Conserve them by walking, cycling and using public transport.

    • 11.7 Renewable and Non-renewable Resources

    Natural resources are what we get from nature; things made by people (bulbs, furniture, solar panels, bicycles) are human-made resources.
    Renewable resources are renewed or restored within a reasonable time — air, water, forests.
    Non-renewable resources are limited and not replenished within a reasonable time — minerals, soil, rocks, coal, petroleum, natural gas.

    11.8 Resources We Use

    Back in the city, the children smell vehicle smoke. Amma mentions electric vehicles that release no smoke. Activity 11.6 lists natural resources behind daily tasks (washing clothes → water; making clay toys → soil; making kites → paper/bamboo from forests).

    "Earth provides enough to satisfy every man's need but not for every man's greed." — M. K. Gandhi

    Activities in the Chapter

  • 11.1 Breathing exercise – feel the need for oxygen.
  • 11.2 Make and decorate a firki – see wind at work.
  • 11.3 Water-wastage table – suggest ways to save water.
  • 11.4 Investigate soil samples with naked eye and magnifying lens (wash hands afterwards).
  • 11.5 Survey vehicles and fuels in your neighbourhood.
  • 11.6 List natural resources used in daily activities.

    • Key Terms

  • Natural resources (प्राकृतिक संसाधन)
  • Human-made resources (मानव निर्मित संसाधन)
  • Renewable resources (नवीकरणीय संसाधन)
  • Non-renewable resources (अनवीकरणीय संसाधन)
  • Wind (पवन) and Windmill (पवनचक्की)
  • Freshwater (मीठा / ताज़ा पानी) and Saline water (खारा पानी)
  • Rainwater harvesting (वर्षा जल संचयन)
  • Stepwell (बावड़ी)
  • Forest (वन)
  • Minerals (खनिज)
  • Fossil fuels (जीवाश्म ईंधन)
  • Petroleum (पेट्रोलियम) and Natural gas (प्राकृतिक गैस)
  • Solar energy (सौर ऊर्जा)

    • Real-life Connections

  • Rooftop rainwater harvesting in schools and societies; stepwells in Rajasthan and Gujarat.
  • Solar panels on street lights and traffic signals; solar cookers.
  • CNG buses and electric vehicles to reduce city air pollution.
  • Tree-plantation drives during Van Mahotsav.

    • Common Misconceptions

  • "There is plenty of water, since two-thirds of Earth is covered by it." — Most of it is saline; easily usable freshwater is a tiny fraction.
  • "Soil is renewable because it is everywhere." — Soil forms from rocks over thousands of years, so it is non-renewable.
  • "A cow gets energy just by standing in the sun." — It gets energy from grass, which captured the Sun's energy.
  • "Machines are natural resources." — They are human-made resources.
  • "Forests grow back quickly." — Restoring a forest takes many years.

    • Keep the Curiosity Alive (Exercise hints)

  • Two-wheelers commonly use petrol; water is renewable while coal, natural gas and petrol are not.
  • Petroleum is non-renewable because it takes millions of years to form and is limited.
  • Cutting trees harms soil because roots no longer hold it and no leaves decay to enrich it.
  • If there were no sunlight for a week, solar panels would not make electricity — the family would depend on other energy sources.
  • Plan to save water in school: fix leaking taps, use mugs/buckets, harvest rainwater from the roof.

    • 💡 Key Learning Points

    • ✓Air (78% nitrogen, 21% oxygen, 1% others), water, sunlight, forests, soil, rocks, minerals and fossil fuels are nature's treasures that sustain life.
    • ✓Only a small fraction of Earth's water is accessible freshwater, so it must be saved and kept unpolluted; rainwater harvesting and stepwells are traditional solutions.
    • ✓The Sun is the main source of energy on Earth; energy flows from the Sun to plants to animals.
    • ✓Soil forms from rocks over thousands of years; rocks are made of minerals from which metals are extracted.
    • ✓Natural resources are renewable (air, water, forests) or non-renewable (minerals, soil, rocks, coal, petroleum, natural gas) and must be used judiciously.

    👨‍🏫 Teaching Tips

    • →Use a 10×10 grid of 100 squares and have students colour 78 for nitrogen, 21 for oxygen and 1 for other gases.
    • →Let every student make a firki and test it in front of a fan; then show a video of a wind farm like Muppandal.
    • →Conduct a water-wastage audit of the school taps and toilets and present suggestions to the principal.
    • →Stage a role-play of the Chipko movement and discuss why the women hugged the trees.
    • →Bring soil samples from a field, garden and roadside for students to observe with a magnifying lens.
    • →Run the vehicle-and-fuel survey as homework and compile a class bar chart.
    • →Hold a renewable vs non-renewable card-sorting game and discuss borderline cases like soil.

    📋 Assessment Questions

    1. Can the student state the percentage composition of air?
    2. Can the student explain why only a small part of Earth's water is usable and suggest two ways to conserve it?
    3. Can the student settle the 'cow gets energy from the Sun' debate with reasoning?
    4. Can the student classify coal, natural gas, forests, minerals, air and water as renewable or non-renewable?
    5. Can the student explain how fossil fuels form and why their overuse is harmful?

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    Keep learning

    All chapters in Curiosity - Science Class 6

    1. 1. The Wonderful World of Science
    2. 2. Diversity in the Living World
    3. 3. Mindful Eating: A Path to a Healthy Body
    4. 4. Exploring Magnets
    5. 5. Measurement of Length and Motion
    6. 6. Materials Around Us
    7. 7. Temperature and its Measurement
    8. 8. A Journey through States of Water
    9. 9. Methods of Separation in Everyday Life
    10. 10. Living Creatures: Exploring their Characteristics
    11. 11. Nature’s Treasures
    12. 12. Beyond Earth