The Language Differential

I am the only native English speaker in my class. That includes the faculty. It's a fine line to walk. I am often torn between trying to help people with words and letting them say things in their own way. Some of my classmates have the same problem in English that I have with German: they understand a lot, but can't really turn it around and speak it easily yet. I am amazed by how quickly they can pick it up. One of the women has only been speaking English for a year and makes very few mistakes. One of the others is learning exponentially. But this past weekend left just about everybody wiped out!
Wolfgang Hartmann was here for the weekend to give us a history of Orff Schulwerk and some additional background on Carl Orff. In between we discussed philosophical issues. It was an intense session and A LOT of English, even for an American.
Everyone thinks it must be so easy for me because the class is in English but as I said before, it's a fine line to walk. How do I say things in ways that people understand? If it's too elementary, it's insulting. If it's too advanced or idiomatic, it's hard to understand. I have to deal with many different accents (so do they!). It's not always a good idea to fill in the blank either.
It's not any different when I try to speak German. I know the words but not the order. And sometimes if you can speak a little with only a slight accent, you get a volley of high speed German in return. But I keep trying anyway. My classmates are reasonably fluent in at least two languages. I should TRY to speak a second one.