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Grade 2 (age 7-8)

grade 2 How Machines Work

How Machines Work

Tools we use to move or lift heavy things more easily are called simple machines. A lever uses a fulcrum to lift something heavy with a small force, and gears mesh and pass on force and speed as they turn. The same ideas hide in scissors, a seesaw, and a bicycle. Press the lever or turn the gears with the sliders and the force changes as it passes on.

Lever — Lifts Heavy Things!

50%
💡 Secret of the Lever
①With a fulcrum, small force lifts heavy things
②Seesaws use lever principle!
③Scissors, bottle openers, nail clippers — all levers

Gears — Transmit Force

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⚙️ Secret of Gears
①Teeth interlock and transmit force
②Big gear → small gear spins faster. Speed goes up, force goes down
③Clocks, bicycles, cars all have gears!

Simple Machines Around Us

🛞 Wheels — Roll for Ease!
①Pushing heavy things on ground is hard
②Wheels make it much easier
③Cars, bikes, suitcases all have wheels
🔧 Inclined Plane — Reach Higher Easily!
①Ramps are easier than stairs
②Slides are inclined planes
③Screws are wrapped inclines — amazing!

Summary

🎯 Simple Machines Summary
①Lever — lifts heavy with small force
②Wheel — rolls easily
③Gear — transmits force, changes speed
④Incline — reach higher easily
⑤Example: a bicycle puts wheels and gears together

Examples and Unit Test

Example 1
Using a lever, how can you lift a heavy object? What must there be?
1
A lever must have a fulcrum (a pivot point).
2
When you push around the fulcrum, you can lift a heavy object even with a small force.
▸ With a fulcrum, you can lift a heavy object with a small force
A seesaw also moves by the principle of the lever.
Example 2
What tools around us use the principle of the lever?
1
Scissors, a bottle opener, and nail clippers are all tools that use a lever.
2
They help us cut, open, or press with a small force.
▸ Scissors · bottle opener · nail clippers (all use a lever)
Simple machines make our everyday life easier.
Unit Test
What must a lever have?
①A fulcrum
②A wheel
③Teeth (gear)
④A spring
⑤Electricity
▸ ① A fulcrum
1
A lever lifts heavy things with a small force around a fulcrum.
2
A wheel is for rolling, a gear for passing on force, and a ramp for raising things to a high place.
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