Grade by Grade
D. Structures and Mechanisms · Simple Machines and Movement

Meet the Six Simple Machines

D2.3 D2.4 A1.1About 30 minutes
Learning goals
  • I can name the six simple machines: lever, wheel and axle, pulley, inclined plane, wedge and screw.
  • I can explain that simple machines help us move things with less force, or move them more easily.
  • I can find simple machines in my home.

Words to know

machine
A tool that helps us do work, like moving, lifting or splitting something.
simple machine
A machine with few or no moving parts. There are six kinds: lever, wheel and axle, pulley, inclined plane, wedge and screw.
work
In science, work means using a force to move something.
load
The thing you are trying to move or lift.
effort
The push or pull you use to move the load.

A heavy problem

Imagine you need to get a big bag of birdseed into the back of a truck. It is too heavy to lift!

What could help? You could lay a long board from the ground up to the truck and slide the bag up. You could put it in a wagon and roll it. Those helpers are simple machines!

A sack of seed resting on a wooden board that leans from the grass up to the back of a pickup truck, with a red wagon nearby.
Two simple machines are ready to help: a board used as a ramp to slide the heavy bag up, and a wagon with wheels and axles to roll it. AI-generated image

What is a simple machine?

In science, work means using a force (a push or a pull) to move something.

A simple machine is a tool with few or no moving parts that makes work easier. A simple machine can help you:

  • use less force (a smaller push or pull),
  • change the direction of your force (pull down to lift something up), or
  • move something more easily, farther or faster.

The thing you want to move is the load. The push or pull you use is the effort.

truckEFFORT: your pushLOAD: the bag of birdseedramp (a simple machine)
The load is the thing you move. The effort is your push or pull. A ramp lets a smaller effort move the heavy load up into the truck.
leverwheel andaxlepulleyinclinedplanewedgescrew
The six simple machines: lever, wheel and axle, pulley, inclined plane, wedge and screw.

Remember from Grade 1

In Grade 1 you learned that a structure holds up a load, like a table holding books. Structures usually stay still. This year we learn about machines that help us move a load.

Simple machineWhat it isEveryday example
levera stiff bar that turns on a pointa seesaw, a bottle opener
wheel and axlea wheel that turns with a rod through its middlea wagon, a doorknob
pulleya wheel with a rope around ita flagpole, window blinds
inclined planea ramp, a slanted flat surfacea wheelchair ramp, a slide
wedgea shape thick at one end and thin or pointed at the otheran axe, a doorstop
screwa ramp wrapped around a roda jar lid, a wood screw
The six simple machines

A trick to remember them

Use your body!

  • Lever: your arm bending at the elbow.
  • Wheel and axle: roll your hands round and round.
  • Pulley: pretend to pull a rope down.
  • Inclined plane: make a slanted ramp with your arm.
  • Wedge: put your hands together in a point.
  • Screw: twist your finger like a corkscrew.
Funny but true

You are a walking toolbox! Your arm bends at the elbow like a lever, and your front teeth work like wedges when you bite into an apple.

Worked example

Let's name the simple machine

What simple machine is a slide at the playground?

  1. Look at its shape. A slide is a flat, slanted surface.
  2. One end is high and one end is low.
  3. A flat slanted surface is an inclined plane (a ramp).
  4. Its job: you climb up the ladder, and the ramp lets you slide down smoothly.

A slide is an inclined plane.

Worked example

Let's sort tools from the kitchen

Which simple machine is each one? knife, jar lid, rolling pin, bottle opener.

  1. Knife: the blade is thin at the edge and thicker at the back. That is a wedge. It pushes food apart.
  2. Jar lid: inside the lid are ridges that spiral around. That is a screw. Twist to close it tightly.
  3. Rolling pin: it rolls on a rod that you hold by the handles. That is a wheel and axle.
  4. Bottle opener: you lift the handle, and it turns on the edge of the cap to pop it off. That is a lever.

Knife: wedge. Jar lid: screw. Rolling pin: wheel and axle. Bottle opener: lever.

Hands-on activity

Simple machine scavenger hunt

You need: paper, a pencil, and a grown-up helper.

  1. Write the six machines down the side of your paper: lever, wheel and axle, pulley, inclined plane, wedge, screw.
  2. Walk through your home (and yard or garage, with a grown-up). Find at least one example of each.
  3. Draw or write what you found beside its name.
  4. Research: Pick one machine you could not find at home. Look in a library book or ask a grown-up where you could find it in your community (a flagpole at school has a pulley!).
  5. Share your list. Explain how one machine makes a job easier.

Ideas to look for: doorknob (wheel and axle), scissors (two levers with wedge blades), knife (wedge), jar lid or light bulb (screw), window blinds (pulley), front steps ramp or a slide (inclined plane). Safety: look at sharp tools but do not touch them; let a grown-up handle knives and axes.

Your turn

1

Name all six simple machines.

2

What does a simple machine do?

3

Which simple machine is a wheelchair ramp?

4

Which simple machine is a seesaw?

5

Which simple machine is on top of a flagpole?

6

What is the load?

7

Which simple machine is an axe?

More practice: warm-up

1

How many simple machines are there?

2

A wagon has wheels on rods. Which simple machine is that?

3

Which simple machine is a jar lid?

4

Is a slide a lever or an inclined plane?

5

What do we call the push or pull you use on a machine?

More practice: on your own

1

Why is a knife a wedge?

2

Name one simple machine you used today and say what job it helped with.

3

A rope goes over a wheel at the top of a flagpole. You pull down, and the flag goes up. Which machine is it, and how does it help?

4

Which two simple machines does a pair of scissors have?

5

Is a hammer pulling out a nail a lever or a pulley?

Challenge

1

A wheelbarrow helps you move soil. Which two simple machines does it use? Explain.

2

Your friend says, "A machine has to have a motor." Is that true? Explain.

3

Think of a big job in your community, like building a house. Name two simple machines builders might use and what for.

Check your understanding

Quiz

1.

Which one is not a simple machine?

2.

A ramp is a...

3.

What does a simple machine do?

4.

Which simple machine is a doorknob?

5.

Which simple machine is a jar lid?

6.

The thing you want to move is called the...

For parents and teachers

Big idea: There are six basic simple machines: lever, inclined plane, wedge, pulley, wheel and axle, and screw (Ontario expectation D2.3). They make tasks easier (D2.4). The next five lessons look at each machine closely. The scavenger hunt includes a small research step (A1.1).

How to help: Do the scavenger hunt slowly and point out machines as you use them: "I'm using a wedge to cut the bread." Many everyday tools combine two machines (scissors: levers plus wedges; wheelbarrow: lever plus wheel and axle). Accept either answer when it fits.

Common difficulties:

  • Thinking "machine" means something with a motor or a plug. Simple machines often have no moving motor at all.
  • Mixing up wedge and inclined plane. Both are slanted. A ramp stays still and things move up it. A wedge is the part that moves: it is pushed into things to split or hold them.
  • Long names. Practise the six names with the body actions in the tip box.