I have found the following approach works well. First, select a topic, such as capital punishment or urban development. Divide a class of 30 into four groups - two as "discussers" and two as "observers". Provide the "discussers" with a focused question, such as "Why do people approve of capital punishment?" or "Why might it be more important to build houses than preserve the countryside?".
While the "discussers" consider possible answers, the "observers" remain silent and make notes on the points raised and anything they notice about the way the group tackles the question. I suggest you get the "discussers" together in a huddle and the "observers" spread equally around them, so nothing is missed and the "observers" do not form a rival discussion group!
After 10 or 15 minutes, reassemble the class and ask the "observers" to report what they have heard. Make comparisons or invite the students to do so. Some steam can be let off by then allowing them to comment on the ways the "discussers" approached the task.
Depending on your curriculum subject and the course the students are following, a plenary may be added in which key points are summarised, omitted details are added, and so on. Not only does this approach help to overcome the problems with class discussions, it also has links with debating techniques and avoids the need for an elaborate, drama-style set-up, which some students find hard to manage. Reverse the roles and the questions in a subsequent lesson to allow for equal opportunities and to ensure that a balanced view of the topics is provided.
Colin Padgett, head of English, The Ramsey School, Essex