The reason for my question is a project on assessing the usability of self-study language learning materials - print and online material - which could be used by adult refugees to learn German as a second language.
The number of teachers for German as a second language as well as the number of facilities at this point is hardly sufficient for offering language courses to all the refugees currently entering Germany. As a result, "some" propose self-study materials as an alternative to language courses. There are quite a few initiatives which now offer online language courses partly for free (e.g., http://www.50languages.com/). However, the question arises to what extent these courses and the materials they provide, are any good for adult language learners. I am well aware that the group of adult learners I am talking about is very heterogenous with respect to previous educational experiences and prior linguistic knowledge. Hence, suitability of materials cannot be generalized to the entire population. Nevertheless, should you have any suggestions for criteria or existing lists of such criteria, I would appreciate your help!