The director that came on to direct the third movie, Alfonso Cuarón, asked the three main characters to write an essay about their character. True to form, Emma Watson (Hermione) wrote a 16 page essay, Daniel Radcliffe (Harry) wrote a one page essay, and Rupert Grint (Ron) didn’t even turn one in.
According to Grint, he…”didn’t do mine, because I didn’t think Ron would. Or that was my excuse. At the time, I was actually quite busy with the real schoolwork involved with my exams, and I just didn’t do it. But in the end, it felt right because that’s what Ron would have done.”