Both sides are being unbearably obstinate here.

The teacher's meaning is clear and the kid should just answer what is being asked, not what is being said. So the kid is in the wrong. If you're smart enough to be this clever, just answer the question.

The teacher says "You are wrong, failed" when the kid is technically correct, instead of clarifying the intent of the question. So the teacher is in the wrong. "Clever, but you know what I meant" solves the problem. "You get an A in math and an F in interpreting language"

On the flip side, I had a cousin who had a question on a test: "What is the largest SI prefix" ... he answered "yotta" (which at the time was the largest)... And got it wrong. because the "correct" answer was "mega". Because that was the largest the class had learned about at the time, and the teacher was very inflexible on this; they acknowledged that yotta was the largest, but my cousin had learned about it outside of class, so it couldn't be an acceptable answer. The teacher couldn't possibly fathom marking "mega" right for students who had only context from the classroom and also marking "yotta" right for students who had done independent research. No, the question was IMPLIED to be "what is the largest SI prefix [that we have covered in class]" and anything else was wrong.