dinis, being 11/12 years old, you won't know why school is so important, but as you get older, and start looking for jobs, you will realise how much it effects you, know...
And school wasn't "invented", "school" used to be a guru spreading his wisdom to followers, which obviously changed to something like a group of people gathering together, and exchanging knowledge, which mumst of changed to meeting in a building, which then must of had a load of rules thrown on it, like ages, the curriculum, and other stuff, like that...
trust me, I know how you feel, im actually only 2 years older than you, but i know why school is so important, i don't like it, and don't get some aspects if it, but i havee to put up with it, if i want a life when i grow older and mature.... well, not really mature, but don't have parents to care for me and buy food, ect,ect......