  Throughout all years of study, students of physics are confronted with the
question 'what exactly is light?' - a question that is impossible to answer
correctly and, therefore, continuously discussed within the framework of
models. Numerous models have been introduced for this purpose and subsequently
compete with one another for validity. On the one hand, this may lead to
learning difficulties. Yet, on the other hand, this may be considered a
didactic chance, if thinking about the model is compounded with the
consideration of models in general. Research in secondary school level II
physics classes and with physics students provides insight into the processes
of model construction as well as that of overcoming models, which will be
presented and analyzed here. The possibilities which computer simulations
provide for the discussion of various models of light are demonstrated and
their influence on a structured construction of models will be discussed.
