Oh boy. Yesterday Kal-El was reviewing indefinite articles. I let him sort the cards first because this was review and he already seemed to know which nouns took "a" and which took "an." After he was finished I asked him to look over his work and then come tell me the rule for which one goes where.
So you don't have to squint at the picture the pairs are:
He looked at it a second and said with confidence, "The nouns that go with 'an' don't make good housepets."
He was NOT joking. Oh dear.
Also heard in our house that day...
Me Too: "I'm really glad I have a butt."