Use green, yellow, and red colored cups for group work. When a table gets too loud, change the cup to yellow. If the table continues to be too loud, the cup gets changed to red; this means a loss of group time. Students now have to do their work independently and silently. This is great and won't punish the entire class.
Math Coach's Corner: Book Study Mondays: Math Sense, Chapter 4, The Look of the Lesson: Students. Join in this online book study and learn how to incorporate the Standards for Mathematical Practice into your math instruction. Free bookmark listing the practices!