bake cookies or cupcakes and sell them at school. if the guys at your school are anything like the guys at mine then you can sell them for like a dollar each or more if they are really hungry. or you can go to the dollar store and buy the dollar bags of candy and sell them for $5. also a car wash with a group of friends, get your moms to help and combine it with something like a bake sell for extra money.
I think that has been a question everyone has asked for thousands of years. You could do work though, like mowing yards and other yard work. Chores for people. All kinds of things. Money won't drop in your lap for nothing, sorry. Good luck.