Teachers and principals of today teach children by sitting them in a chair for an hour and a half a block and making them listen. Teacher's rarely interact with the students. The future of the world is in the hands of us students, and they're still teaching us old methods. Teacher's alienate millions of children across the world, teaching them useless things such as algebra and how to find the area of a triangle.
Teacher's set unrealistically high goals for students and when they don't reach the goal, make them feel like they're not smart enough, or not a good enough student, and that they're stupid. Albert Einstein once said "Everybody is a genius, but if you judge a fish by its ability to climb a tree, it will live its whole life believing that it's stupid."
School systems today are very old fashioned, and judgemental. The government thinks that all kids learn at the same pace, and at the same age, should have the same knowledge as other children their age.