Encapsulation and modularity are supported by various static access control mechanisms that manage implemen- tation hiding and define interfaces adapted to different client profiles. Programming languages use numerous and very different mechanisms, the cumulative application of which is sometimes confusing and hard to predict. Teach- ing these concepts requires precise and comparable definitions of the mechanisms used by the languages taught. We present here our experiences with access graphs, a notation we use for teaching encapsulation and modularity in object-oriented languages.