Student roles in differentiated group activities will change slightly depending on the activity they are doing. It is important to have students hold certain jobs during differentiated group activities to keep the group rolling forward and not get distracted.
A couple of roles that should always be included are task master and time keeper. The task master acts as the motivator and policeman of the group. When a student gets off topic or sidetracked the task master redirects them. There should always be an amount of time allotted to finish the assignment. Otherwise the students will take advantage of it and waste time. The role of the time keeper is to frequently tell the group the amount of time they have left to finish the assignment. This will again motivate the students to stay on task. For most activities there will be a writer. Teachers need to make sure that this role is not misused by the other students in the group. They are to be used more like a secretary who writes down the groups ideas. They themselves are not responsible for the end product and all the critical thinking that goes along with it. Other roles might be an artist, speaker and material gatherer. No matter what activity it is, roles should be assigned to students because they help group activities go smoother and be more productive.
http://www.teacherspayteachers.com/Store/Kasha-Mastrodomenico/Category/Activity-Templates-and-Rubrics helps social studies teachers differentiate instruction in less than 10 minutes by using activity templates with rubrics, check it out!