The moodle gradebook recognizes the existence of groups in a moodle course. This filter option is especially useful when different teachers are responsible for providing assessment for a subset of students in a single moodle course.

In order for the filter options to appear, groups mode must first be enabled and groups already created in the course.
See "Enabling and Creating Groups in Moodle"

1. In the Settings block, select "Grades" under "Course administration".
   
   
   
   
2. From the groups pull down menu in the upper-left corner of the grader report, select a group to view.
   
   
   
   Only the participants in the selected group will show in the grader report.