The British Board of Film Classification (BBFC) is  a group of people that are responsible for certificating movies.
The are in charge of saying whether a film is a PG or a 18 and so on. One of our lessons we had to analyze several sequences from different film including Up, Harry Potter and The Chamber of Secrets and Watership Down. We then had to decide if they were PG or U, as they were all children films. There was only one U out of the several sequences which was Up. Up was certified a U because of the of slapstick that was fortunately censored if it was shown to a younger audience. The other sequences were certified as a PG. We know that Harry Potter and The Chamber of Secrets was a PG because it contained hardly any violence, cursing, discrimination or unappropriated images.  There was a sequence from "Watership Down" Everyone was shocked at how much blood and violence it had during the sequence, when it is after all a childrens film. The British Board of Film Classification rated Watership Down a  PG which is making everyone think it should really be rated "12" considering the content it contains, even though it wasn't made recently like the others were.