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Science for Kids: Learn About Simple Machines

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When you think of machines, you probably think about cars, diggers, or robots. If you had to find machines around your house, you might point out the washing machine, dishwasher, and television. A fork or a flight of stairs might not come to mind. But forks and stairs are also machines. A machine is a device that makes a job easier to do.

Simple Machines affect the force or amount of effort needed to do a certain job. They make it easier because they require less force or they apply force in a direction that's easier to control. As an example, a hammer makes it easier to put a nail into a piece of wood.

A simple machine is a machine that isn't powered by electricity, batteries, or an engine. There are several types of simple machines:

  • Pulley
  • Lever
  • Wedge
  • Screw
  • Wheel and axle
  • Gear
  • Inclined plane
A pulley is a type of simple machine many kids may be familiar with

A pulley is a type of simple machine many kids may be familiar with


Imagine you have to take a heavy bale of hay up to the second floor of a barn. You could try taking it up a ladder or stairs. But bales of hay are big and heavy. It would be difficult to drag one up a ladder or steps. A simple machine called a pulley can make a bale of hay easier to move.

A pulley uses a wheel and axle with a rope or chain to pull an object. The rope or chain fits into the wheel, and one end of the rope is attached to a heavy object like a bale of hay. When you pull on one side of the pulley, the wheel turns and the bale moves.


Think of a lever as a board resting on an object. The object the board rests on is called a fulcrum. A seesaw is a type of lever. A door hinge is also a type of lever. A hinge makes it easy to move a large and heavy door.

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Think of someone splitting firewood with an axe. The axe is a wedge. Wedges are used to cut an object into pieces. When you eat with a knife and fork, you are using wedges. You use your knife and fork to split food into smaller pieces to make it easier to eat.


You're probably familiar with screws that hold things together whether that's furniture or the battery compartment cover on a toy. A screwdriver is used to put in or take out these screws. Screws have a spiral-shaped thread that can easily bore into wood. But these aren't the only types of screws. The end of a lightbulb, fan blades, and helicopter blades are all types of screws.

Wheel and Axle

A wheel and axle has two parts: the wheel (the round part) and the axle (the rod that goes through the center of the wheel). When the axle turns the wheel spins round and round.

Inclined Plane

An inclined plane is a slope or ramp. Inclined planes make it easier to move objects up or down. Stairs are inclined planes. They make it easier for people to move to higher or lower places. Wheelchair ramps are another type of inclined plane. The steeper an inclined plane is the more force that's needed to move up. Imagine pushing a rock up a ramp. The steeper the ramp is the harder you will have to push to move the rock.

Simple Machines Games


This content reflects the personal opinions of the author. It is accurate and true to the best of the author’s knowledge and should not be substituted for impartial fact or advice in legal, political, or personal matters.

© 2014 JoanCA

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