Take a proactive approach to group management with get-to-know-you games and silly claps. Here are a few we like:
Move Your Booty
Circle up. One person begins in the middle and says a fun fact about themselves: "Move your booty if you love playing four square at recess" or "Move your booty if you have been to Michigan." If true for you, move from your spot in the circle. The person who doesn't make it to a spot leads the next fun fact.
Silly Claps
Need no explanation. :)