These objects are organized in more complex entities, such as conceptual systems, theories, etc. The six types of primary objects postulated widen the traditional distinction between conceptual and procedural entities that is insufficient to describe the objects intervening and emerging from mathematical activity.The problem-situations promote and contextualize the activity; language (symbols, notations, graphics, ...) represent the other entities and serve as tools for action; arguments justify the procedures and propositions that relate the concepts. These entities have to be considered as functional and relative to the language