Purpose of School

School suppose to educate the mind of children to be open, free-thinking, and critical?

But, the school is also a "perfect" systematic way to brainwash the children's mind to be what society wants of them. And people do utilize school for this end, while the open mindedness, free and critical thinking may ruin their wish.

Well, what a paradox. Isn't?

So, which one is the true purpose of a school?