As noted above, students aren’t disinterested interlocutors. And very often they are acting in “bad faith,” to use Satre’s term. That is, they are running from their freedom and responsibilities. They are shopping for an endorsement from an authority figure when they need to start taking responsibility for the hard work of moral discernment and the resultant consequences of their behavior.
I would add that if you have to ask if a given action is a sin, it most likely is. I say this because asking that question trying to get a “green light” from an authority figure indicates that the given act would violate your own conscience