I have 2 students in one of my classes and all they behave as if they haven't seen each other for years, talking on and on, while I am trying to present a lesson. I use different strategies to get these 2 to settle down without embarrassing them or calling even more attention to them. First, I get them involved in the lecture or presentation itself; this way they are actually talking on topic and, in giving their opinion, they are taking center stage. Second, when this doesn't work, I call attention to them by asking if there is anything they want to add or tell th class; while this could potentially be embarrassing, it is not for these 2 and they are always more than ready to comment on any subject. The best way to deal with "talkers" is to get them to talk on target and not just chit-chat to each other.