The teacher can also have an effect on group dynamics.
Example
The group dynamics of a class can change enormously when a new learner or teacher joins the class.
In the classroom
In the language classroom, the teacher needs to recognise which of the factors that contribute to group dynamics are within their control, as not all are. Teachers can contribute to positive group dynamics through choosing relevant aims, topics and appropriate activity types, and establishing a good rapport.
Further links:
https://www.teachingenglish.org.uk/article/grouping-students
https://www.teachingenglish.org.uk/article/working-pairs-groups
https://www.teachingenglish.org.uk/article/involving-whole-group-lesson
https://www.teachingenglish.org.uk/article/group-work-v-whole-class-activities