LYDIAN is an environment to support the teaching and learning of distributed algorithms. It provides a collection of distributed algorithms as well as continuous animations. Users can combine algorithms and animations with arbitrary network structures defining the interconnection and behavior of the distributed algorithm. Further, it facilitates the creation of algorithm descriptions as well as the creation of network structures. This makes LYDIAN a flexible tool to be used with students with different skills and backgrounds. This article gives an overview about various ideas and concepts behind LYDIAN by describing in detail the framework for an educational visualization and simulation environment for learning/teaching distributed algorithms as well as discussing possible extensions, which may improve possibilities for user interaction. Moreover, in our effort to understand better what visualization and simulation environments, such as LYDIAN, need to provide, we show results taken from a case study integrating LYDIAN in an undergraduate distributed-systems course.