Introduce the rules
Introduce the rules that must be followed during group work, first of all the definition of roles: transcriber, speaker, moderator, time guard.
Defined roles apply to group work in all subjects (see activities 6, 8 and 12 for examples of group work).

Role cards discussion
Prepare role cards with brief explanations of the roles and the duties with pictures e.g. a clock for the time guard. Have a class talk to read them with all the learners.
When introducing the defined roles for the first time via class talk, learners should think and talk about who could do which role best, who could help or fit in best. Sometimes they need a little help but normally they can assess their characters quite well.

It would be useful that before the assignment of a task or topic, learners have the possibility to identify which are the most appropriate roles to accomplish, with the help of a questionnaire, according to their skills, interests, and character.

Keep the roles for the whole group work
During a single group work learners are not allowed to change roles. Throughout the year, for other group works they are allowed to change roles, in order to be fair towards each other especially when a group member can do a specific role better than other members.