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Before we talk about complex machines, let's review what a machine is.

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Machines are instruments which help us perform a job a lot faster.

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The earliest machines were invented a long time ago.

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Examples of some of these machines are the wheel, the pulley, and the lever.

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We call these simple machines because they don't have many moving parts.

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What complete machines can you use now?

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All machines need energy to function.

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This energy can come from people or sources of nature like water, the sun, or gas or oil.

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Or machines can get energy from electricity.

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Can you name three different sources of energy?

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Complex machines can have many, many parts.

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These machines are made of multiple simple machines that work together.

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For example, in this picture with the crane, we can see it has wheels, a lever, and pulleys.

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What simple machines can you find in the picture?

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Here are some examples of complex machines.

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A washing machine. This uses electricity to wash our clothes faster than if we were to wash our clothes by hand.

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A tractor. This uses gas or oil to perform agriculture jobs.

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And an airplane transports us to faraway places.

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How would we get to the United States from Spain if we didn't have an airplane?

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It would take a lot of days.

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Do you have any complex machines in your room?

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Do you have any simple machines in your room?

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Machines are always evolving.

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They usually start out simple and become complex and more advanced over time.

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For example, cars didn't always used to look the way that they do now.

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People used to travel by horse and carriage.

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In the next picture, we can see the first car model, and it doesn't need a horse to power it.

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This car became more advanced with a roof and sides, as you can see in the yellow car.

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And the final picture is what most cars look like today.

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Can you think about a complex machine that has evolved from the invention until now?

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Life is so much easier with the help of machines, don't you think?