Lesson 3: Simple Machines
Simple machines make work easier by changing the direction or size of a force. There are six classic simple machines and they are found in almost every tool ever invented.
Key Concepts
Lever
A lever is a bar that rests on a pivot point called a fulcrum. A seesaw is a lever. Scissors are two levers. Moving the fulcrum closer to the heavy side makes lifting easier.
Wheel and Axle
A wheel and axle multiplies force. The steering wheel in a car is much bigger than the axle it turns — a small turn of the wheel moves the axle a lot. Doorknobs, rolling pins, and wheels are all examples.
Inclined Plane, Wedge, Screw
An inclined plane (a ramp) lets you move heavy things up gradually using less force. A wedge is two inclined planes joined (an axe, a knife). A screw is an inclined plane wrapped around a cylinder — it converts rotation into linear motion.
🆕 Lever Simulator
Drag the fulcrum to see how it changes the effort needed to lift the load!
✅ Check Your Understanding
1. What is a simple machine?
2. What is the pivot point of a lever called?
3. What is a ramp an example of?