The Individual Rating for Group Projects is a rating guide or rubric which is appropriate to use with middle school and/or high school level. It has also been successfully used on the college level by me and my colleagues in the math department.
Here is how it works. Students first rate themselves using six particular criteria based on a rating ranging from 1-10. They then evaluate each member of their group using the same criteria.
The rubric may be used for co-op groups, group projects, collaborate oral presentations, partner lab work - anytime a group must work together to produce one final product. By averaging each student's scores from the group and including it as part of their final project grade, each student's participation, work, and contribution to the group becomes a part of their final grade.
This document is not save in a PDF format so that you can adapt it for your classroom.