Three points earned, not given

Years ago, one of my high school teachers asked an unexpected extra credit question on a history quiz.  The last of 10 questions was "Write the first verse of your favorite Christmas carol."  Those who claimed "Rudolph, The Red-Nosed Reindeer" was their favorite didn't get credit because they wrote, "Rudolph, the red-nosed reindeer, had a very shiny nose..."  As the teacher pointed out, the first verse is actually, "You know Dasher and Dancer and Prancer and Vixen..."  That's one of the more unusual reasons I've ever heard for denying students extra credit.  Also, although the teacher didn't bring this up, "Rudolph" is technically a song, as opposed to a carol, such as "Silent Night" or "The First Noel."