Common grade-school activity in American physical education classes (in between the dodgeball and games of “red light, green light”). Get an old canopy-style parachute silk from an army surplus store. The kids all grab a piece of the edge and whip the center up in the air. They then all get under the chute and pin the edges down. The chute retains air for a long time (the point of a parachute), and thus there’s 2-3 minutes where the kids are in some freeky alternate world where vision is limited and various games involving running around and accidentally colliding can occur. Yet another way that phy ed very rarely means “getting exercise” but very often means “being distracted and getting blunt trauma.”