Often group conflicts aren’t revealed to the instructor until the end of the project. Encouraging or requiring progress reports or feedback from students at specific intervals may help you to identify trouble spots.
For semester-long projects, a mid-semester feedback form is useful. In “Online Groups and Social Loafing: Understanding Student-Group Interactions,” Piezon and Donaldson suggest including multiple evaluation points so that “group members are aware that their contributions are salient and being observed by others. Members who are performing poorly are given several opportunities to increase their performance.”
Another strategy is to prevent conflicts by keeping the groups on track and on task by requiring small deliverables for the project throughout the semester.