A single speck of dust is half way in size between a subatomic particle and the Earth.
15
When you walk down a steep hill, the pressure on your knees is equal to three times your body weight.
199
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
During photosynthesis, plants emit light humans can’t see, but NASA can see that light from space - and they've even made maps of it!
21
Iron weighs more after it rusts.
68
Sound travels about 4 times faster in water than in air.
408
Iron weighs more after it rusts.
16
One gallon of used motor oil can ruin approximately one million gallons of fresh water!
71