He hated school because Mark's experiences in school weren't so good. Whippings are a daily experience, and Mark is frequently punished because he talks too much or his nails aren't clean or his school fees aren't paid on time. And he hates homework.
3.This has a clarifying effect in depicting the terrible situation in the apartheid in South Africa. Because he wants to portray the horrible and unfair that life can be just for the fact that the color of your skin is different.
4.-Mark isn't impressed when Mama tells him he'll be going to school. He believed school was a waste of time, a lesson he learned from the gang of boys who lived in a junkyard and spent their days searching for food and stealing things for money. Where the boys were growing up, education wasn't valued, but figuring out how to fight and steal was. He uses active verbs like believe, learned, lived to depict what he thought about school.
5.-Since he wanted to make something more formal in his protest and it would imply more people involved and more time, too.