To be honest, it depends on how responsible a student is. I myself is a still a student who relies in Bitcoin to help me finance myself but I for once haven't forgot about my studies and had an average grade of B+. You should consult your students and approach them to give them some advice. It's not Bitcoin's fault but it was students entirely. 
Yes, it really depends on how student discipline himself. Personally, I am so happy to do both studying and bitcoining since I am motivated to learn because fees, and other payments will not be hard for me because of bitcoin. And I dont think bitcoin will be a hindrance in my study. Students must know their priority.