Activating students as learning resources for one another
Use peer feedback (Note: easier said than done. Perhaps ask a consultant to help you lay the necessary foundations in your class to make this happen)
Provide sentence starters (e.g. "I think it would be clearer if...")
Start with peer assessment of anonymous work
Start in pairs before going into larger groups (e.g. think pair share)
Prioritize individual accountability in peer assessment (and in group work)