The first step to having this conversation, was the designing of an activity that would bring the key issues to the surface. In this instance the focus was how students collaborate. A simple of trick of asking the whole class (25 students) to do a task that would be easily completed by a smaller group, say 5 students. The pressures of working in a large group are much more acute, it's almost like setting them to struggle ,as the pressure ( and previous experiences) will see them focus on the content rather than the process. The students in this lesson where asked to construct a food web out of 25 organisms.
The lesson began with the students and I compiling a list of what they think good learners do when they collaborate. This list is theirs and I always ask permission to provide feedback on it using a thumb up for agreement, a level thumb for something they can live with and a thumb down if they want to amend the list before I use it for feedback. The list has now turned itself into success criteria.
The students then "do" the activity, and I write down observations snippets of conversations, counts of number of points, the number of people who are talking at the same time etc. I use one Post it note per statement, and in this lesson I did it for 15 minutes. A tight time scale is another way inducing students to forget about the process and make the mistakes that may not always be an issue in smaller groups.
At the end of the challenge, I give feedback and ask questions about the content of the activity and gather the students around their previously agreed success criteria. At this point I ask for permission to add a "disappointments" column, adjacent their success criteria. I then read out my observations one by one stressing that I am not making any judgements, just giving them factual feedback. I ask them to direct me in placing each statement on either the success criteria it matches, (for example " Great idea Tom!" May be placed on we encourage each other) or in the disappointments column.
The students really pay attention to this, I think they feel a little empowered. They also feel a little chastised as they are a lot more critical of themselves than a teacher ever could be. This is why a safe and trusting classroom environment is needed. For example some quiet students will not force into this kind of activity preferring to keep silent. Some members of the class will feel it i their fault, but others will see the groups responsibility to invite everyone to participate. This is kind of dialogue that find this strategy engenders and that changes students view and participation in the activities.
It is not just collaboration that this works on you could have questioning, decision making, reasoning, risk taking, the list goes on, but the strategy works.
For a more detailed read about this technique in my classroom please search it out on http://www.peelweb.org/. typing in author search MEAD.