Here is some advice for the person coordinating the post-lesson discussion.
Ideally the post-lesson discussion can be held in the same classroom as the research lesson, so that participants can use student work or refer to materials used in the lesson.
About an hour has been found to be a productive length of time for a discussion. However, if everyone is still actively engaged and enjoying the discussion, and it is possible, you may find it beneficial to go on longer. The person chairing the post-lesson discussion will need to use their judgment and take the advice of the hosting teacher who may have other lessons to teach. This is a good reason why it might be helpful to have the research lesson as the last lesson of the day.
Introducing the discussion (for the chair of the session)
§ Begin by reminding everyone of the research focus of the lesson. Try to keep discussion focused on this.
§ Ensure that everyone has copies of the lesson plan and any observation notes they have taken.
§ Give the teacher an opportunity to talk about their own perceptions of the lesson and any reasons they had for deviations from the lesson plan in response to student learning during the research lesson.
§ Ask for brief-but-vivid accounts of critical incidents, encouraging participants to describe what they saw, rather than attempting to account for why. This keeps the discussion open to alternative explanations and avoids premature closure.
§ Discourage participants from making evaluative judgments about "what went well", or otherwise. Each point made should refer to evidence seen in the lesson. At this stage it may be that participants refer to their own experience of teaching the same lesson with their students if they have been able to do so.
Structuring the rest of the discussion
Following this introductory phase there are many possible ways of continuing the post-lesson discussion:
§ Plenary throughout. This way, everyone hears everything that everyone says, but with a large number of observers this can be time-consuming. Keeping everyone focused on the research question helps.
§ Think-pair-share. Participants could have a few minutes to think individually and write down their thoughts (perhaps on post-it notes) before sharing with another participant. This could be a helpful prelude to plenary discussion.
§ Group discussions. One possible way of proceeding is to divide into small groups to explore different aspects of the research question, perhaps collecting thoughts on a flipchart or poster, and then reconvening to share what has emerged.