Look into memrise.
It has an app, it has a lot of the bells and whistles that Anki lacks (like a scoring/gamification system) that could be helpful with the population you are teaching, and it is all around a solid SRS system. The only thing I think it lacks are those Easy/Good/Hard buttons that Anki has to differentiate between how well you know the answer, but that's something I can live without. I use both it and Anki on a day to day basis.
I just played around with Memrise, and it does indeed look perfect for my audience. I had begun my SRS search with gwern's excellent exploration of the topic, where Memrise does not appear. Thank you so much!
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.