Maybe I am a little bit of your topic, but I got to say this:
Try teaching German, it's far more complicated then English or Chinese, there are rules which even I as a native speaker can not explain. I mean I got used to this rules just be growing up. For example, the use of articles. In English you just say "the tree"/"the
trees". In German you switch the article. In singular you say "der baum" in plural "die baeume"! Try to explain this to someone else, how shall anybody know the f***ing plural forms.
German, from my point of view, after having put myself into learing English, Latin, Spanish, Italian, Chinese and Japanese, seems to be an language which is far more difficult to learn than those other languages. Everybody who's willing to learn another languages
has to be admired, but anybody learning German and getting along with it pretty well, well respect.