12 Things you learned in school that have since been proven wrong

Deoxygenated blood is blue

A misconception about blue deoxygenated blood is surprisingly pervasive, althoughhuman blood is always red due to a large number of red blood cells. It is true that our veins look blue, but it only happens due to the way the wavelengths of light are reflected from your skin: the red light is absorbed and the blue light is reflected.