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 I agree that it depends on how responsible student is. If he/she know his/her priorities then it does not effect his/her performance in school. But parents should guide their childrens about it.