My 2c: Just asking for / accepting students won't work.
School work is about having explicit, rigid goals and structure so that the work and progress can be evaluated and graded. Supporting materials are available, covering all the expected problems, and there is someone to consult with, whose job is being there for you. You know where you start and where to go.
Open source is generally a chaotic movement in the general direction. When you have time and motivation, you help pushing, when not, you are not needed. Information is scarce and you are expected to look yourself before asking, since no one is compelled to take care of you. You do what's fun for you.
These are two rather incompatible cultures. Usually you need someone who dedicates himself to taking care of the students - and screen them to get rid of these who would sink like a stone without constant support. In the best case, a student already taking part in an open source project decides himself to try getting credit for cheap out of his hobby.