For face-to-face classes, one technique I use is to have students discuss the topics in groups of 3 or 4(random groups, usually done through slips of colored paper). Then the group posts the summary of their discussion to the BB Discussion Forum. As a class, we look at the different submissions and have a class discussion about them. The length of time needed to do this depends on the topic. It can take as little as 20 minutes -- good to use at the beginning of class to "set the stage" for the lesson.