Interesting fact:

Much like their characters, Daniel Radcliffe, Emma Watson, and Rupert Grint were all quite different when it came to schoolwork. Before the filming of Prisoner of Azkaban, director Alfonso Cuarón asked each of the actors to write an essay about their character. Radcliffe wrote a page, Watson wrote 10, and Grint didn’t write anything. When asked, Grint recalled “I didn't do mine, because I didn't think Ron would.”