Talk to her about her. Talk about school, music, things you have in common.
o.k. if you want to talk to your girlfriend about interesting thing you got to make sure she is fully paying attention to you. Then instead of talking to her about school(unless she likes it) talk to her about interesting things that happenend to you in your life and ask question about her. Talk about what you got in common foods, music, t.v. shows, animals, ect.