The paper proposes an agent-based computer simulation as a supplementary tool for teaching the principles of microeconomics. Such simulation can graphically illustrate how the individual behavior produces the studied aggregate outcomes, can bridge the gap between the abstract theories and the real world, and can mitigate the emotional aversion students have against some theories. The approach is demonstrated on a case of allocation of a scare resource: the model is described, the simulator is created, and its features are analyzed. The simulator has been made available on the Internet for free.