Each round, each student decides how many fish to catch from an open-access lake (a common-pool resource). The tragedy of the commons occurs when overfishing prevents the sustainability of the fish stock for future use.
Teach students about common pool resources and how self-interested use can cause harm to others (by creating negative externalities) and result in a tragedy of the commons.
In this game, the primary societal cost of overfishing is borne in future periods as the fish stock dwindles. For a game where over-exploitation of a common-pool resource reduces current payoffs, see MobLab’s Tragedy of the Commons game.