We don't do unit plays either b/c the campers only stay a week.
We do however have a session called "Spotlights On" for 5th-7th graders who plan and preform a play.
Our camp has an entire "Costume Closet", with tons of dress up clothes so we often bring our units there to play around and do little skits for each other. If they are good we might have the campers preform their skit at the closing campfire.
