The reason for this is because he did not follow the normal procedure of learning nor agreed with how everyone else thought. For this he was considered a "bad pupil" as he also put no effort into subjects which he disliked. For example, Einstein often daydreamed in classes that he was not interested in but was an absolute maths genius. He mastered calculus at just 15 years old and dropped out of school. He was not dumb, Einstein was very smart and is a prime example of why the school system is not for everyone.
