This video shows the process Chris Opitz, a teacher in Alaska, uses to encourage math discussions in his classroom. I am sure every day doesn't go as smoothly as this video makes it seem, but I'm willing to bet the benefits are worth the challenges.
This approach looks like it would make a very flexible classroom. I can see many ways of adapting groups and pairs to address differentiation and intervention. It also appears there would be more opportunity to help students understand concepts and encourage deep thinking.
This video was created in 2008. I would love to see a follow-up from this teacher. What problems did he face? How has he tweeked his approach? Has he seen that his approach improves learning for his students?
If you like his approach, check out this page on Edutopia. It includes downloads of materials Chris uses to organize his class.
Have you tried this approach in your classroom? I'd love to hear more about the challenges and successes you've experienced. From outside the fishbowl, this looks like a great way to manage a class, keep kids engaged, and help students learn at the deepest level they are able.