Punh him around some! Tell him you're gonna whip up on him every day until you get paid!
First of all don't do silly things like cutting up his bag and books, coz it doesn't help you to get your money back and it may do you more harm than him. It depends how much he owes you, but if it's worthwhile give him a week to pay you back and tell him that if he doesn't you will contact his parents, or the headmaster of your school, or ultimately threaten him that you will report him to the police.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.