IMHO students will more benefit from studying/reading open source software code than trying always to contribute. University is a big time commitment with coursework, exams, labs, which is unavoidable to graduate.

Open source is a great source of learning; architecture choices, battle tested real-world software. So, if a student asks for my opinion, I would say fork it, clone it, study it and if you find something to contribute, great submit your pull request.