BLOOD
You need blood to keep your body working. If you don't have blood you would die instantly. The average adult has about five liters of blood. There are two types of blood cells white and red.
Interesting fact #1: Blood is blue/green when inside your body. Once it touches air the blood turns RED
Interesting fact#2: Blood type is inherited just like hair color or eye color.
Interesting fact#3: Different animals have different types of blood. For example, dogs have 4 types of blood, cats have 11, and cows have about 800.
Interesting fact#4: There are four types of human blood. A, B, AB, and O. Each letter refers to a kind of protein.
Interesting fact#5: Blood is alive. Blood is alive because it contains living cells.