Checks and balances

I told you before that using red pens is "bad" in Korea, but that I am supposed to correct/grade papers in red. Well the other day I handed some tests back to some kids and they all gasped. I was like, what? because they had done ok. They asked what checks meant and I said correct. I was then informed of the following meanings for symbols on school work:
                                 Korea          US
check                       -wrong         - right
X                              (not used)     - wrong
circle around words  - correct      - this is the area I'm talking about/what's this
star                        - I don't know  - very good
?                            (not used)        - I don't know

I told them I use checks for right. They said, but we're in Korea. I said this is English school, so checks mean right.

Totally different topic:  They have a product here which I can't believe we don't have the in US (or if we do, I've never seen it): Cheese Ramen. It takes ramen noodles and adds flavor packet like the cheese in instant mac & cheese. It is awesome.