Chalk, it dedicated its body to education. It uses its own body to make ignorant and naughty children learn to read, learn morality, learn to understand and learn humility ... just like teachers, they work hard to educate the next generation for the future of the motherland.
A hymn about Fenbid:
"Crayon Zan" Pang Shengze (Modern)
A small one, a thousand words in one step; At sunrise and at sunset, I go away, and the sunset glow is fragrant and I speak freely. Look into the eyes of knowledge, pity and ease, and try your best to laugh at wax dust.
Extended data
Chemical composition of chalk:
Chalk is made of hydrated calcium sulfate (commonly known as gypsum). You can also add various pigments to make colored chalk. In the production process, raw gypsum is heated to a certain temperature to partially dehydrate to form plaster of Paris, then the plaster of Paris is stirred into paste with water, and then poured into a mold for solidification. The reaction of plaster of Paris to plaster of Paris is (heating):
Calcium sulfate 2H2O = calcium sulfate ·H2O+H2O
The reaction between gypsum plaster and water to form gypsum plaster is (normal temperature):
Calcium sulfate H2O+H2O = calcium sulfate 2H2O
References:
Baidu encyclopedia-chalk