If the important aspects are selected, complexity is reduced in a fruitful and helpful way. If unimportant are aspects are dominant, the result can be completely misleading. When using simulations, care has to be taken to select the right model and to make the adequate choice of important aspects. A specific aspect of simulations is the fact that users are given the opportunity to interact with the program through interfaces. These interfaces should be as userfriendly and transparent as possible to let the user get in direct contact with the content.
Immediate feedback is presented with the smallest possible delay or change of environment.
There is a broad agreement about the fact that learning, which goes beyond pure memorizing, is based on an activity on the side of the learner. Knowledge cannot be implemented or transferred, it has to be reconstructed to have any long lasting effect. Simulations offer an opportunity for interactions, they deliver immediate feedback on user actions, stimulate exploratory learning. The chances for active learning are definitely increased in comparison with normal textbooks or non-interactive media. It is well know and most plausible that hidden relations between different facts are best learned if these related facts are presented as closely as possible together in space as well as in time.