In this paper, we describe the evolution of an interactive technology called the Ecological Modeling Toolkit (EMT) that supports learning about complex ecological systems in middle school science. Authentic learning of science is facilitated by imitation, rehearsal and understanding of real-world scientific practices such as observation, experimentation, problem formulation, hypothesis testing, and model construction and revision. We illustrate how the tools in EMT work together to support many real-world scientific practices such as model construction, simulation and revision, and scaffold others such as observation, problem formulation and hypothesis testing.