I try to use open discussions in all of the topics that I am teaching. By asking questions I can usually figure out which students are really listening and which students are not. I try not to pick on any one person, because I do not want them to feel embarressed or ashamed if they really don't know the answers. I find that to be a very fine line to cross. If we are reviewing for an upcoming exam, I usually get a good response from the students. Most of them are eager to answer the questions however there are those who will just stay quiet and take notes. I don't like to put the students on blast.