Glena Iten investigates the impact of interactive visual simulations on conceptual understanding of statistical principles. Overall, all students were able to increase their knowledge by working with visual simulations, whereas students who could manipulate statistical graphs in the simulation on their own were significantly faster. Currently, interactive learning tools explaining statistical concepts are widely spread, but only few are tested. Well-structured interactive learning programs with visual simulations have in the past been shown to be effective. By applying effective instructional design principles, an online tutorial where students could either manipulate or only observe changes in the visual simulations, was developed. Practical implications and opportunities for further investigations in this research project are discussed.