Class 4 EVS Chapter 7 How Things Work – Revision Notes

Class 4 EVS Chapter 7, How Things Work, introduces students to simple machines and everyday mechanisms — levers, wheels, pulleys, and springs — and how they make tasks easier.

Last Updated: September 23, 2026

About Chapter 7: How Things Work

Everyday objects like scissors, see-saws, doors, and bicycles rely on simple mechanical principles. This chapter builds curiosity about how common tools and machines function, using observation and hands-on thinking.

Key Concepts

1. Levers

A lever is a simple machine that helps lift or move things with less effort, pivoting around a fixed point (fulcrum) — seen in see-saws, scissors, and bottle openers.

2. Wheels and Axles

Wheels reduce friction and make it easier to move heavy loads, especially when paired with an axle — seen in bicycles, carts, and vehicles of all kinds.

3. Pulleys

A pulley uses a wheel and rope to change the direction of force, making it easier to lift heavy objects — seen in wells, flagpoles, and cranes.

4. Springs

A spring stores and releases energy when stretched or compressed, returning to its original shape — used in pens, toys, and door hinges.

5. Why Simple Machines Matter

Simple machines make daily tasks easier and faster by changing the amount, direction, or speed of the force needed to do work, without requiring complex technology.

Quick Recap

• A lever pivots around a fulcrum to make lifting or moving easier.
• Wheels and axles reduce friction, making it easier to move loads.
• A pulley changes the direction of force to help lift heavy objects.
• A spring stores and releases energy, returning to its original shape.
• Simple machines make daily tasks easier without needing complex technology.

Common Mistakes to Avoid

Students sometimes confuse a lever and a pulley since both help with lifting — the key difference is that a lever pivots around a fixed point, while a pulley uses a wheel and rope to redirect force. Encourage identifying the fulcrum, wheel, or spring in each example to tell the machines apart clearly.

How to Practise This Chapter at Home

Identify and test simple machines around the house — a pair of scissors (lever), a door hinge (spring-like mechanism), a bicycle wheel (wheel and axle), or a bucket-and-rope well (pulley) — and discuss how each makes a task easier. Try a simple see-saw or lever experiment using a ruler balanced on a pencil.

Why This Chapter Matters

Understanding simple machines builds early engineering and scientific thinking, showing children that everyday tools are not “magic” but follow understandable, observable principles that can be explored hands-on.

Frequently Asked Questions

What is a fulcrum?
The fixed point around which a lever pivots or turns when force is applied.

How is a pulley different from a wheel and axle?
A pulley uses a wheel and rope mainly to change the direction of a force (like pulling down to lift something up), while a wheel and axle mainly reduces friction to help movement.

What are some everyday examples of levers?
Scissors, see-saws, bottle openers, and nutcrackers are all common examples of levers.

Why do bicycles use wheels?
Wheels reduce friction with the ground, making it far easier to move forward compared to dragging or sliding.

How does a spring store energy?
When stretched or compressed, a spring holds energy due to its shape change, and releases that energy as it returns to its original form.

See the Chapter 7 Solutions for the full textbook walkthrough.

Written by Satish

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