An earthquake is one of the worst natural disasters on our Earth. We think that the ground we stand on is very stable, but it isn’t. It moves quite a lot. In the last few decades, scientists have been able to find out why earthquakes happen.

Earthquakes happen when there is a sudden vibration in the Earth’s crust. It’s like a large lorry that travels down your street. When it passes by, you feel your house shake.

Contents (23 pages)

• Introduction
• How plates move
• Where earthquakes happen
• Earthquake waves
• How earthquakes are measured
• Effects of earthquakes
• The greatest earthquakes in history
• Exercises
• Word list
• Key

Series of earthquakes in East Azerbaijan in 2012
Image: Mardetanha, CC BY-SA 3.0, via Wikimedia Commons

Electricity is the flow of tiny charged particles, mainly electrons, through a conductor, like a wire. It creates an electric current that powers our many devices and machines that we have in our household, from lights to computers.

Contents (22 pages)

• Introduction
• Parts of an atom
• Conductors and insulators
• Electric currents and circuits
• Types of electricity
• How batteries work
• Hoe electricity is produced
• How electricity is measured
• Power lines and transformers
• Electrical safety
• Exercises
• Word list
• Key

Image: FreeSVG.org , Public Domain