Not sure if this is the right place to ask this question, but here we go. In my college I like talking to people and making connections. I think I am an extrovert. Sometimes when I talk with other students I like to say “hey, how are you?” with a big smile. A lot of people just respond with a smile and they don’t reply back. Yesterday I asked two people how their vacations went, they barely said anything and just smiled a little bit. They didn’t ask me how my vacations went.
I live in the northern part of Italy. I don’t know these students very well. We go to the same classes and we sit almost next to each other, we know each other's names and have said exchanged greetings like 'hi' a few times. I don’t hang out with them outside of class. This happens quite often with the same people (pretty much every time). These people are very outgoing with the group they hang out with. But they kind of shy away when they leave third group.
I’d like to know how to get to know these people, so how to do so when they don’t respond to greetings the way I would expect them to?