# When is a door not a door? A Common Core math riddle

A frustrated parent posts a photocopy of a page from a math workbook at the Facebook page Common Crud, along with a verbal “sigh”:

This is part of tonight’s 2nd grade math homework. I’m not sure how a second grader is supposed to have any clue why the flat surfaces on a rectangular prism are called faces. I don’t know why. And the answer was nowhere to be found on the paper.

According to the category heading that precedes the problem, the kiddies are supposed to arrive at an answer by means of the skill of reasoning. Come, let us reason together.

Putting aside entirely the appropriateness of this question for Grade 2, how is this a math question and not, say, one of etymology or philosophy? A search for answers, in any case, yields a couple of possibilities.

A commenter at the open-ended website WikiAnswers writes:

The flat surfaces of all polyhedra are called faces and a rectangular prism is simply one kind of polyhedron.

But that just raises the question of why the flat surfaces of polyhedral are called faces.

A commenter at the similarly open-ended Brainly.com posits:

The flaat [sic] surfaces on a rectangular prism are called faces because they are the main side of the object. The word faces comes from the Latin word facies, meaning the main side of something.

Even if we accept that second-graders are going to be familiar with the Latin root of this word, it’s still more an etymological question than of math, and there’s no way to answer it by an appeal to simple reason.

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### Howard Portnoy

Howard Portnoy has written for The Blaze, HotAir, NewsBusters, Weasel Zippers, Conservative Firing Line, RedCounty, and New York’s Daily News. He has one published novel, Hot Rain, (G. P. Putnam’s Sons), and has been a guest on Radio Vice Online with Jim Vicevich, The Alana Burke Show, Smart Life with Dr. Gina, and The George Espenlaub Show.