Ummm... WHAT?

Tonight Brendon is practicing his spelling words (we're going over the words) and I ask what word goes w/ the definition *being calm while waiting for something* and all this week he's given me the same answer--PATIENT. Which is technically right, but for homework it's PATIENCE. So I tell him, yeah but it's patience. Then I'm saying things like I'm being patient, or I have patience. Trying to make a point that they're used differently.. yadda yadda.
Then he says ---yeah, a patient is at the dr's office. yes, you're right. then he says yeah, those words are homonyms!! I'm all what? He says, they're homonyms. And so I ask him what the crap is a homonym???? And he gave a pretty close definition of what it was, that they sound the same & are spelled different or something. He was pretty close, and knew what it meant. So I asked him--where the crap did you learn the word homonym??? And my freakin' kid looked at me & did a finger pointing/twirl thing and said, SCHOOL.... DUHH!!!!