How Things Work — Class 4 EVS (CBSE)
From the current NCERT Our Wondrous World Grade 4 book, Unit 4: Things Around Us, Chapter 7. Many clever tools and simple machines make our daily work easier.
1. Why this chapter matters
We use many tools and simple machines every day without thinking about them. Learning how they work — and how they make tasks easier with less effort — helps children understand the objects around them and use them well.
2. Key ideas
- A tool or simple machine helps us do work with less effort.
- Common simple machines:
- Lever — a see-saw, a bottle opener, a crowbar (lifts or moves things).
- Wheel — carts, bicycles, and trolleys roll easily on wheels.
- Pulley — helps draw water from a well or raise a flag.
- Inclined plane (ramp) — a slope makes it easier to move things up.
- Everyday things work in simple ways: a tap controls water, a switch turns things on/off, scissors cut.
- Most tools work by a push or a pull.
3. Let's understand
Think of lifting a heavy load. A lever, like a crowbar or a see-saw, lets us lift it with less effort. A wheel lets a heavy cart roll instead of being dragged. A pulley helps us pull up a bucket of water from a deep well. A ramp (inclined plane) lets us push things up a slope more easily than lifting them straight up.
We also use simple things at home. A tap lets us start and stop water; a switch turns a light or fan on and off; scissors cut paper neatly. Most of these work with a simple push or pull.
These tools and machines are clever helpers — they save our time and effort and make daily work easier.
4. New words
| Word | Meaning |
|---|---|
| tool | a thing that helps us do work |
| simple machine | a basic device that makes work easier |
| lever | a bar that helps lift or move a load |
| pulley | a wheel with a rope to lift things |
| effort | the force or energy we use to do work |
5. Activity corner
Look around your home and school for simple machines. Write:
- One lever, one wheel, and one pulley you can find
- What each one helps you do
- Whether it works by a push or a pull
6. Common mistakes
- Mistake: Thinking machines must be big and electric. Fix: A see-saw, a bottle opener, and scissors are simple machines too.
- Mistake: Saying tools make work harder. Fix: Tools and simple machines make work easier (less effort).
- Mistake: One-word answers for "how does it help" questions. Fix: Say what it does, e.g., "A pulley helps lift water from a well."
7. Let Us Think
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What does a simple machine do for us? It helps us do work with less effort.
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Name two simple machines and what they do. A lever lifts or moves a load; a wheel helps things roll.
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How does a pulley help us? It helps lift things, like drawing water from a well or raising a flag.
-
How does a ramp make work easier? It lets us push things up a slope instead of lifting them straight up.
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Name two things at home that work by a switch or tap. A light/fan (switch) and water (tap).
8. Answer key
- It helps us do work with less effort.
- Lever (lifts/moves); wheel (rolls).
- It helps lift things like water from a well.
- It lets us push things up a slope more easily.
- A light or fan (switch); water (tap).
9. Quick revision
- Tools and simple machines make work easier (less effort).
- Lever, wheel, pulley, and ramp (inclined plane) are simple machines.
- Taps control water; switches turn things on/off; scissors cut.
- Most tools work with a push or a pull.
- Simple machines save time and effort.
Unit 4: Things Around Us
This chapter is part of Unit 4: Things Around Us. The two chapters in this unit are:
- Chapter 7: How Things Work
- Chapter 8: How Things are Made
