Even students who don't have a green thumb can grow and study an entire forest by downloading SimForest from Hampshire College in Amherst, Massachusetts. Aimed at 7th graders and up, the free virtual ecology program lets users seed a silicon ecosystem with combinations of more than 30 tree species and adjust environmental variables such as rainfall, temperature, and soil type. Long-term forest dynamics unfold on the screen, allowing students to gauge the response of their woodlands to climate change and other disturbances and to study processes such as succession, or gradual change in the types of trees. The software uses models from the literature, and advanced students can download a version of the program that allows them to adjust the equations. Sample curricula help teachers integrate SimForest into high school and college classes.