Information units -- in MediBook the notion MediaBrick is used -- are associated with concepts, whereby each MediaBrick is described by metadata. Furthermore MediaBricks are associated with each other by rhetorical- didactic relations in such a way as to put them into a context -- e.g. MediaBrick A 'deepens' MediaBrick B -- thus building the MediaBrickSpace. Since in MediBook we are dealing with educational content we use the Learning Objects Metadata (LOM) [1] for the description of the information units.