ActiveMath is a complex web-based adaptive learning environment with a number of components and interactive learning tools. The basis for handling semantics of learning content is provided by its semantic (mathematics) content markup, which is additionally annotated with educational metadata. Several components, tools and external services can make use of that content markup, eg, a course generator, a semantic search engine and user input evaluation services. The components and services have to communicate, pass content and state changes, actions, etc including mathematical semantics and educational markup. The novel event infrastructure supports this communication. This paper focuses on the usage of the content's semantics by selected novel components and sketches the communication.