Harry Potter: 10 Majorly Dumb Plot Holes You Never Noticed
4. The Whole School Is Like The Room Of Requirement
What caused it: The movie's shortsightedness. Although the varying numbers of students which fans often complain about come from Rowling not being too bothered by it when writing the books.
We see Hogwarts properly in seven movies and throughout that time it never stays the same. Chris Columbus films for the most part stuck to the same model, but then along came Alfonso Cuaron, throwing out many elements from Philosopher's Stone and Chamber Of Secrets. Not necessarily a bad thing.
Adding in the covered bridge, clock tower and courtyard that would prove the centre of much action in later years (despite never appearing in the book), Cuaron pushed Hagrid's hut further from the school and overall increased the grandeur of the place. After his changes, the floodgates were open and subsequent directors Mike Newell and David Yates continued to add elements to the castle and grounds as they saw fit.
Obviously in the book Rowling was free to add and remove things as she pleased; you could just amend your imagination of the castle. In the films, however, we really needed some more consistency. It's not necessarily a bad thing; Hogwarts needed to be bigger for the events of the later books, but it's a tad lazy.