Lightning never strikes the same place twice.

Sound travels faster through water than through air.

Water boils at 100 degrees Celsius at sea level.

Humans use only ten percent of their brains.

A diamond is made of pure carbon.

Glass is a slow-flowing liquid, which is why old windowpanes are thicker at the bottom.

Cracking your knuckles causes arthritis.

Sound cannot travel through the vacuum of space.

The Sun is a star.

Summer happens because Earth moves closer to the Sun.

Earth has seasons because its axis is tilted.

Helium is lighter than air, which is why a helium balloon rises.

Hair and fingernails keep growing after a person dies.

Eating sugar makes children hyperactive.

Rust forms when iron reacts with oxygen and water.

Blood inside your veins is blue until it meets the air.

A bolt of lightning is hotter than the surface of the Sun.

Plants take in oxygen and give out carbon dioxide during photosynthesis.

Ice floats because water expands as it freezes.

Antarctica is classified as a desert.

The Moon has a side that never receives any sunlight at all.

A coin dropped from a skyscraper would kill someone walking below.

An adult human skeleton has 206 bones.

You lose most of your body heat through your head.

Oxygen makes up about a fifth of the air we breathe.

Sunlight takes about eight minutes to reach Earth.

Water spirals down a plughole the opposite way in the Southern Hemisphere.

All deserts are hot and covered in sand.