The paper discusses the relation between accessibility and multimodality of learning objects. I present a framework, rooted in linguistics, that supports a clear distinction between content and expression of learning objects. The framework supports different types of content elements, and different expression elements in which content can be rendered, which include different expression media, multimedia components and spatial/temporal/hyper-relationships. I show what accessibility means in such a framework, and what the consequences of accessibility are in terms of automatic transformations of expression that can occur on student platforms. I argue that accessibility of learning objects, though making them multimodal, is not a satisfactory solution from the viewpoint of learning effectiveness. I claim that content modeling needs to be a crucial step in the development of any learning object, and propose notations based on conceptual maps and UML diagrams.
