Cooperation is important to creating a peaceful, safe environment. Balloon volleyball is an activity children can do as a group. It's also a great intergenerational activity. For older adults, it has physical and therapeutic value (e.g. hand-eye coordination, range of motion, flexibility). It's a simple demonstration of how a group must work together to achieve a goal -- in this case, preventing a balloon from touching the floor.
People can all stand in a circle with the common goal of keeping the balloon in the air using their hands. When the balloon heads in your direction, it's your turn to give it a swat.
Variation: Make two teams. Teams face each other and try to keep the balloon off the floor on their side of a dividing line.