1) An 11-year-old boy named Trevor comes up with an idea called "Pay It Forward" for a school assignment where people can help others without expecting anything in return to make positive change in their community.
2) Trevor helps several people as part of his idea, including a homeless man named Jerry and his classmate Arlene. However, his efforts are not always successful and face challenges from doubters.
3) Eventually, Trevor's teacher Mr. Chandler tracks down the origins of a growing "Pay It Forward" movement in the community to Trevor, but sadly Trevor is fatally stabbed while defending a friend from bullies.