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Class 3 · Environmental Studies

Air and water

🧊 Explore in 3D: Food and waterEach topic: a spark, a 3D scene, an explanation, practice, a real-life task and reflection. ▶ Open topic

📘 Chapter notes

The key ideas of this chapter, answered through the six guiding questions. Read them with your textbook.

🧠 Concept map: Air and water
airwindwater vapourpollutionevaporationAir and water
1What am I looking at?

Answer: Air and water around us and why we need them.

2What are its main parts or ideas?

Answer: Air is everywhere, takes up space and moves as wind; water exists as ice, water and vapour.

3How does it work?

Answer: Wind turns windmills and dries clothes; water evaporates when heated and condenses when cooled.

4Why is it important?

Answer: All living things need clean air and water.

5What happens if something changes?

Answer: Smoke makes air dirty; garbage makes water dirty.

6What should I remember for the exam?

Answer: Properties of air and water and causes of pollution.

📗 Full lesson: Water and air

This topic comes from GayaGnan's India-wide K–12 catalog. It is not copied from, or an official chapter of, any board's textbook: check your board's syllabus for the exact chapter and depth. Open as its own page →

🌧️Water cycle

🎯 Learning outcomes

  • Explain the water cycle with evaporation, condensation and precipitation
  • Describe the composition of air and its uses
  • Explain causes of water and air pollution and ways to conserve water

Before you start: Sources of water; air is around us.

📖 Explanation

Water moves in a cycle. The Sun heats water in seas, rivers and lakes; it evaporates into water vapour. High up, vapour cools and condenses into tiny droplets forming clouds. When droplets join and grow heavy, they fall as rain, hail or snow (precipitation), and flow back into rivers, seas and underground.

Air is a mixture of gases: about 78% nitrogen, 21% oxygen, small amounts of carbon dioxide, water vapour and dust. Oxygen is needed for breathing and burning; plants use carbon dioxide; moving air (wind) turns windmills and helps birds fly.

Sewage, factory waste and plastic pollute water; smoke from vehicles and burning pollutes air. We can conserve water by rainwater harvesting, drip irrigation, fixing leaks and reusing water.

🇮🇳 Example from India

Chennai made rooftop rainwater harvesting compulsory for buildings to refill groundwater after repeated water shortages.

⚠️ Common mistake

✗ Water disappears when puddles dry up
✓ The water evaporates into the air as water vapour and later returns as rain.

🧪 Try this activity

Cover a glass of ice-cold water and watch droplets form on the outside. Explain where they came from (condensation of water vapour in the air).

✍️ Question bank with answers

Tap an option to check multiple-choice answers. Open “Answer” or “Marking points” for the others.

  1. Multiple choice 1 mark · easy

    Clouds form by

    Answer

    A. condensation

    Water vapour cools into droplets.

  2. Multiple choice 1 mark · easy

    Which gas is most plentiful in air?

    Answer

    C. nitrogen

    About 78% of air is nitrogen.

  3. Multiple choice 1 mark · easy

    Which saves water on farms?

    Answer

    D. drip irrigation

    Drip irrigation gives water directly to roots.

  4. Very short answer 1 mark · easy

    What gas do we need for breathing?

    Answer

    oxygen

  5. Very short answer 1 mark · easy

    Name one cause of water pollution.

    Answer

    sewage, factory waste or plastic in rivers

  6. Short answer 2 marks · medium

    Why are wet clothes dried faster on a sunny, windy day?

    Marking points
    • Heat speeds evaporation
    • Wind carries away the vapour

  7. Long answer 4 marks · hard

    Draw and explain the water cycle using the words evaporation, condensation and precipitation.

    Marking points
    • Sun heats water and it evaporates
    • Vapour rises, cools and condenses into clouds
    • Droplets fall as precipitation
    • Water collects in rivers, seas and underground and the cycle repeats

  8. Application 2 marks · medium

    Suggest two ways your school can save water.

    Answer
    • Rainwater harvesting from the roof
    • Fix leaking taps; use water from washing for plants

  9. Diagram / label 2 marks · medium

    Draw a pie chart of the gases in air.

    Answer
    • Nitrogen about 78%
    • Oxygen about 21%
    • Other gases about 1%

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