Is he interested or just nice?

I (22F) work as a teacher in a private institute, I’m a pretty extroverted person and I usually get along with all of my students (they all differ in ages because it’s an English school)
I try not to get involved that much with them because they are my students but at my age I think it’s pretty inevitable.
I find one of my students very attractive physically (M20) but I didn’t want to make a move because he is my student and it would be awkward but we ended up following each other on instagram. He’s very quiet and usually does not make conversation until you ask him something but he is always nice and polite.
I DMed him catching up with something we were discussing in person and we’ve been texting since then.
I do not know if he’s just being nice or if he is interested.
I really do not want to make him feel uncomfortable.