Stop, Collaborate and Listen....

That lyric doesn't really make sense but this link I just came across does :)
While Microsoft's ITL Rubrics for 21st Century Learning provide a useful framework for assessing collaborative learning tasks the following article provides some simple yet effective questions you can ask yourself when deciding whether the tasks you have planned are truly collaborative or are just involve pupils 'working together:
http://www.innovatemyschool.com/ideas/eight-ways-to-assess-your-collaborative-learning-tasks