Blind children, can still read, they read using Braille. Each letter in the alphabet has a certain amount of dots in a special pattern. Blind children touch the dots with their fingers to understand what it says.
Deaf children use sign language to understand what people are telling them, since they can't hear. You use different hand motions to represent different words.
Louis Braille went blind at the age of three. Based on his experiences he invented the system of Braille in 1824. He invented the system while still being in the National institute for blind children.
Did you know that to this day people use machines to engrave Braille in books, or reading materials. The machines are engraved with six dots, which make up the alphabet in different patterns.