We have developed a method of using simple, commercially available computer simulations to create productive writing cases. Students working with the simulations easily understand their data, audience, and objectives, and they revise intelligently and successfully. We have used The Farm Game, simulating frontier farming in Nebraska, Fur Trader, simulating the life of a Canadian courier du bois, Hamurabi, simulating government problems in a Sumerian city state, King, simulating economic decisions on a Caribbean island, and Stock Market, simulating trading of amplified stocks. We are expanding our library of programs, and we will be happy to serve as a clearinghouse for exchanges of simulations useful to writing teachers.