Collaboration is a 21st Century skill, and despite the social nature of today's youth, it doesn't come easy. Leaders need to learn how to delegate work and direct people in an effective way. Shy students need to learn to speak up. Socialites need to learn to stay focused on the task at hand. Group projects are a great opportunity to learn collaboration skills, but they can also be disastrous, especially when it comes to grading. Its inevitable--someone doesn't pull their weight in the group, the group gets a low grade, and suddenly its 'not fair'. While the old adage is true, life is not fair--group grading should be.
Last year I experimented with a grading style that helps to avoid this. Rather than grading the entire group at the end of a project, I grade the students individually based on their contribution. I formatively assess throughout the project, and by the end of the project I usually have a pretty good idea of who has done their work.
In addition, I like to design my projects so that each group member is responsible for an independent part of the whole final product. In the end, the group must find a way to put all of their work together into one presentation. Its important to make each independent part so that the other group members don't rely on the completion of another student's work. For example in my recent project Exploring the World Project, students had to research the most amazing physical features in the Eastern Hemisphere. They each had to make several presentation slides, create a map, and create a written explanation of how each physical feature formed. The group had to combine their work into one presentation, map, and written paper. Of course Google makes this very easy. When the group presented, each group member presented their independent parts. When they were finished, we graded out individually. Life was finally fair.