Another user recently asked whether there was an easy way of transferring students from their Year 7 classes to their Year 8 classes: https://www.duolingo.com/comment/16641762
As far as I can tell, she's going to have to do so manually, one student at a time. A lot of sites allow teacher users to create their student accounts by uploading a CSV file. Would it be possible to introduce something like that?
Failing that, would it be possible to alter the interface so that students can be dragged from one class to another? Or perhaps to be able to select and move several students at once?