This online tool re-implements the World3 computer model from the seminal 1972 study "The Limits to Growth" by Meadows et al. at MIT. The model calculates how five key global variables-population, natural resources, pollution, food production, and industrial output-interact over 300 years (1900-2200). Using real, historical data through 2024, it conveys how exponential growth in a finite world inherently creates feedback loops of either sustainable equilibrium or system collapse. Explore three scenarios: Business as Usual, which represents their original prediction of collapse around mid-century; Stabilized World, which shows how policy changes create sustainability; and Technology, which shows innovation-driven growth. The model calculates each year dynamically, making it a powerful teaching tool for understanding complex systems, sustainability, and the long-term consequences of our choices.