When I was growing up one of my best friends was Chinese. (In fact, I'm pretty sure he still is.
) One time our parents decided the families should get together, so we took turns having the whole family over for dinner. At my buddy's house we had traditional Chinese food; which meant a bowl that you would hold up above the table and eat from. My mom smacked me and told me to watch my manners; when she noticed that everybody else in his family was eating the same way. (I had been over to his house for dinner several times at that point.)
I suppose if you aren't aware of other cultures, it may seem odd. But I think in this case the teacher went a little overboard.