This is a simple game for parents and teens that "forces" group dynamics into play. 

The supplies you will need are blindfolds for everyone and rope at least 20 feet long (based on group size). 

Blindfold everyone, parents and teens.  Place a length of rope in everyone's hands.  Challenge them to form a perfect square while blindfolded using the full length of the rope.   They are finished only when everyone is touching the rope and agrees that it's a perfect square.

You watch, notice, and highlight who the leaders are, who listens well, who doesn't listen well, etc.   This may be your lesson or an intro to something deeper.