A good rule of thumb is that the greater the percentage of the group grade that goes towards each student's individual grade, the more closely the instructor has to monitor the progress of the groups. If you have a large class that prevents you from following the progress of each group, then do not make the group grade percentage too high.
For a group to function effectively, everyone has to play a positive role. But only the group members themselves can really evaluate how well the group is functioning.
Ensure that each student is individually accountable with little possibility of having free rides.
It may seem paradoxical but ensuring that each individual is accountable for learning the work is one of the most important elements of successful group work. Failing to ensure this is one of the most common causes for the breakdown of collaborative group work. Learning is ultimately an individual process but well functioning groups can help each person learn.
There are several ways that an instructor can build in accountability.
It is a good idea to do a group evaluation early on in the group project in order to bring to the surface any latent problems that may exist before the project is too far along.
At the end of the project, the group is required to evaluate how well each person in the group is contributing to the group effort. In other words, how well each person is behaving, according to your own list of criteria for good group behavior.
If the group project is worth 100 points, the group product itself will carry a common grade that counts towards 80 points of your individual grade.
The remaining 20 points is determined as follows. For a four-member group, you will be given 80 points and you as a group will decide how these points are to be distributed by the members of the group by consensus.
If the group feels that everyone contributed equally to the class group work, then each will get 20 points added to whatever points the group got for its project (out of 80). If the contributions were not equal, then the point distribution should reflect the unequal work load. The decision is up to the group. The instructor will intervene only if there is a disagreement that cannot be resolved by the group.
As a group, you will hand in a sheet (signed by each member of the group) to the course instructor giving distribution points to each person in the group according to how much each person assisted the group to function well.