Among the interesting things turned up by my investigation into IF for teaching is a German-teaching module (by Brett Shelton, David Neville, and Brian McInnis at Utah State University) designed for students who natively speak English.
I haven’t gotten very far into the game itself, but I was really intrigued to see this. It starts off with an English-language tutorial voice who steps the player through making commands in German, and I found this very successful (though, obviously, I am not a member of the target audience). In fact, I thought it was better than the average IF tutorial because of the two-language aspect: I had to type back the commands for looking, taking things, dropping things, and so on, but because this parroting was in German, it was more interesting and didn’t feel so zombie-like.
It’s intriguing stuff, I thought. It’s meant for students who have already had a little introductory German, but the first portion at least is playable even if you don’t know very much vocabulary.
Emily Short's Interactive Storytelling 