Most Helpful Girl
I would suggest approaching them at a place where it is normal for you to be. For example, when they are getting food, go to the same place where they are eating and try to strike up a casual conversation (don't flirt first, this may freak them out). Do this for a few days (I know, patience), and hopefully they will invite you to sit with them (I can't think of another way for you to get to know them without being too forthcoming). This is the best idea I have, I hope it helps.