Machines and inventions

A machine is an instrument that makes work easier.

Simple machines and complex machines

Simple machines often have one or two parts.

Complex machines have more than two parts.

Sometimes they are a combination of different machines.

- burn fuel

The printing press.

Made from animal skins

The invention of the printing press meant that many books could be made at the same time.

It was the information revolution.

We read printing books and we also read electronic books.

Was invented about 250 years ago.

People built railways to connect cities in European countries and in the US.

Machines help us in different ways.

Workers need to follow special safety rules.

Electricity flows through metals, water, trees and people.

These materials are conductors.

Plastic, glass and rubber, block the flow of electricity.

They are insulators.