Sound is caused by vibrations from a source such as a voice.
(Vibrate means move from side to side)
These make the air vibrate.
Which makes your ear drum vibrate and you can hear it!
Watch the video below to see and hear it in action…
Sound needs a material to travel through.
This is because there needs to be a material to vibrate.
Some materials are better at letting vibrations through than others.
Sound travels fastest through solid materials like metal and wood.
It travels quite fast through liquids like water.
It still travels through gases like the air.
Sound does not travel at all when there is no air, like in space. This is called a vacuum and would be completely silent.
Use the Powerpoint below to find out more about these properties of sound:
Follow these hyperlinks to learn more:-