Articulating thought in computer-based media is a powerful means for\nhumans to develop their understanding of phenomena. We have created\nDynaLearn, an intelligent learning environment that allows learners to\nacquire conceptual knowledge by constructing and simulating qualitative\nmodels of how systems behave. DynaLearn uses diagrammatic\nrepresentations for learners to express their ideas. The environment is\nequipped with semantic technology components that are capable of\ngenerating knowledge-based feedback and virtual characters that enhance\nthe interaction with learners. Teachers have created course material,\nand successful evaluation studies have been performed. This article\npresents an overview of the DynaLearn system.