The virtual world provides a useful experimental space in which learners can experience the design parameters of a real world task. The importance of the simulated space is that it enables the learner to explore their solution to a design task. This chapter explores some educational opportunities offered by virtual world simulations, and presents a conceptual framework to guide their design and implementation. The framework is illustrated by exploring three contrasting simulation examples. In particular, the examples explain how simulations within virtual worlds can be linked to real world performances and provide an efficient way of developing difficult concepts. The examples outline different types of simulations: an exploratory simulation for learning socio-scientific inquiry; a role play simulation involving an ethically toned situation; and a design simulation in which learners test and refine their ideas for subsequent creation using concrete materials.