pay it forward is a book, written by catherine ryan hyde, which was later made into a movie of the same name. in the movie, a young boy, trevor, was challenged by his teacher to come up with an idea that could change the world and put this idea into action. trevor decided to do a kind deed for three different people. these people then did the same to other. each of these three people then did the same good deed for three other people. as a result, trevor's one good deed led to nine acts of kindness and so the cycle continued.