Collaboration among teachers as a team approach is an important tenet of the concept of Professional Learning Communities, or PLC's, as they are called in education circles. The idea of PLC's is that a school will endeavor to become less a building full of teachers shutting their doors and doing their thing and more about teachers--and administrators--working together to plan lessons, analyze assessment data, determine what reteaching might be needed to move on to other concepts, and planning from there. In early childhood, assessment looks different than say at a middle or high school level, but the concept is the same. The key is to have administrators who are willing to tweak and redesign schedules so that teachers have collaboration time embedded in the day. I've seen collaboration attempted before school, after school, and during the day, and the only school which did it well was the one during which it was embedded.