I actually think that was what it was.
In one strip, an American student is crushed to see so many wrong answers on his last test, only for the teacher to explain that a circle means that the answers are correct. What follows is an explanation of how Os and Xs are viewed in countries around the world, eventually leading to the PlayStation controller and its shape-labeled buttons.
That makes a lot of sense. I've also seen incorrect answers on a test in Japan be marked with a Check Mark symbol. i.e. this:
In the US, I expect that to mean it's right, but it'd mean it's wrong in Japan.