How Things Work – Class 4 The World Around Us Chapter 7 Notes & NCERT PDF

Class 4The World Around UsChapter 7NCERT book: Our Wondrous World - Class 4

Notes and a simple summary of Chapter 7 of the NCERT Class 4 The World Around Us book, with the official chapter PDF, flashcards, an MCQ quiz and an AI tutor for your doubts.

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Chapter 7: How Things Work

Chapter 7: How Things Work

Introduction

Chapter 7 begins Unit 4, Things Around Us. Meera and Dhruv love finding out how things work. One Sunday, Meera spins a coin, and the two go on to explore spinning objects, spinners, and why some things float while others sink. The chapter is all about trying things out, observing and wondering "why?".

What's in this Chapter

Things that spin – Children spin a coin, a bangle, a pencil, a piece of stone, a wooden spinner (top) and an eraser. They record "I observe" and "I wonder". For example, a coin starts to shake as it slows down. Coins and bangles spin, but erasers do not spin properly.

Making spinners – Using cardboard, toothpicks and a pen tube, children make spinners:

  • a toothpick at the centre,
  • a toothpick away from the centre,
  • a square spinner,
  • a circular spinner with a circular mark.

    • The spinner with the hole at the centre looks the same from all sides, stays upright and spins; the one with the hole away from the centre does not. A square card looks circular while spinning. When a spinner is painted with different colours and spun, the colours look different. The book says children are not expected to know the "correct" theory, only to try, observe and suggest reasons.

    Spinning around us – Ceiling fans and potter's wheels spin. A charkha (spinning wheel) twists cotton fibre into thread, and Mahatma Gandhi used it to make handmade clothes. Spinning tops have been used in India for thousands of years; earlier they were made of clay, and the popular lattu is usually made of wood.

    Floating and Sinking – After the rain, Meera and Dhruv float paper boats in a puddle. Some float well and some flip. Children guess, then test, whether a leaf, an iron nail, an empty steel bowl, a stone, an empty closed bottle and a bottle full of water float (F) or sink (S). Heavy things like iron nails sink and light things like leaves float, but not every heavy thing sinks and not every light thing floats. Floating depends on other things too.

    Shape matters – Aluminium foil floats when spread out or shaped like a cup, but sinks when pressed tightly into a ball. So changing the shape can make an object float or sink.

    Make a boat – In groups, children make boats from paper, cardboard, ice-cream sticks, clay, coconut or walnut shells, hold a boat exhibition, and compare strengths and challenges.

    Key Ideas

  • Some objects spin well and some do not.
  • A spinner spins best when balanced, with the stick at the centre.
  • Floating or sinking does not depend only on heavy or light.
  • The shape of an object can change whether it floats or sinks.
  • Trying, observing and asking questions is how we learn how things work.

    • Activities from the Book

  • Spin objects and fill in "I observe / I wonder".
  • Make and colour different spinners.
  • Guess and test floating and sinking objects.
  • Shape aluminium foil three ways and test it.
  • Build a boat and hold an exhibition.
  • Classify wax, cork, potato, marble, lemon, coin, ice-cube and more as float or sink.

    • Words to Learn

  • Spin (घूमना / लट्टू की तरह घूमना) – turn round and round quickly
  • Spinner (फिरकी) – a toy that spins
  • Balance (संतुलन) – being steady, not tipping
  • Float (तैरना) – stay on top of water
  • Sink (डूबना) – go down in water
  • Predict / guess (अनुमान लगाना) – say what may happen
  • Observe (अवलोकन करना) – watch carefully
  • Charkha (चरखा) – a spinning wheel for making thread
  • Aluminium foil (एल्युमिनियम पन्नी) – thin shiny metal sheet

    • Tips for Parents & Teachers

  • Let children spin coins, bangles and bottle caps and talk about what they see.
  • Make a cardboard spinner together and try the toothpick in different places.
  • Fill a bucket with water and test kitchen items: first guess, then check.
  • Press the foil ball very tightly, as the book advises, so it traps little air.

    • Common Mistakes

  • Saying "heavy things always sink" – shape and other factors matter too.
  • Thinking a square spinner looks square while spinning – it looks circular.
  • Pressing the foil ball loosely – air stays inside and it may float.

    • 💡 Key Learning Points

    • ✓Objects like coins and bangles spin, while erasers do not spin properly; a coin starts to shake as it slows down.
    • ✓A spinner with the stick at the centre is balanced and spins upright; a square spinner looks circular while spinning.
    • ✓The charkha and spinning tops like the wooden lattu show that spinning has long been part of Indian life.
    • ✓Whether an object floats or sinks does not depend only on being heavy or light.
    • ✓Changing shape changes floating: spread-out or cup-shaped foil floats, but foil pressed tightly into a ball sinks.

    👨‍🏫 Teaching Tips

    • →Start by asking every child to spin a coin and describe what happens as it slows down.
    • →Keep cardboard, toothpicks and adhesive ready so every group makes at least two spinners.
    • →Do not expect correct theory; accept children's own explanations and ask 'how can you test it?'
    • →Let children change the toothpick length and card position to improve their spinners.
    • →Before each float/sink test, ask children to write their guess first.
    • →Help press the foil ball tightly so the result is clear.
    • →End with a class boat exhibition where each group shares strengths and challenges.

    📋 Assessment Questions

    1. Can the child name objects that spin well and objects that do not?
    2. Can the child explain why the spinner with the hole at the centre spins better?
    3. Can the child predict and then test whether objects float or sink?
    4. Can the child show how changing the shape of foil changes whether it floats?
    5. Can the child ask good 'why' questions about a spinner slowing down?

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    All chapters in Our Wondrous World - Class 4

    1. 1. Living Together
    2. 2. Exploring Our Neighbourhood
    3. 3. Nature Trail
    4. 4. Growing up with Nature
    5. 5. Food for Health
    6. 6. Happy and Healthy Living
    7. 7. How Things Work
    8. 8. How Things are Made
    9. 9. Different Lands, Different Lives
    10. 10. Our Sky