From the mid-90s to the present day, children worldwide have wished they had received a letter inviting them to attend Hogwarts, preferably with Harry Potter—but what if there was actually more room at Hogwarts than you thought, for the most depressing reason possible? In 2000, Rowling said emphatically that there are one thousand students enrolled in Hogwarts at any given time. Since Hogwarts educates children from basically 5th-12th grade and divides them up into 4 houses, that divides up to about 35 kids per house per year. 

But, if you count up all the named characters in the books and kids you see in the film, there are only about 18 Gryffindor students in Harry's class, roughly half the number there should be. Now, granted, the movie is a movie and Warner Brothers wasn't going to cast 1000 kids to just stand around and crowd the shot. BUT—and this is the Internet and young adult fantasy, so there's always a "but"—WHAT IF IT WAS FOR REASONS?

Sources: marauders4ever | geeknation