In this fourth part of a study of the relevance of existing knowledge about child development to social science curriculum development, some tentative suggestions are made for incorporating some of the fundamental ideas of Piaget into a teaching strategy. The ability of children to deal with classifications on the basis of single discrete attributes and their later ability to make multiple classifications and relationships are discussed. Reversibility and reciprocity, as intellectual operations which are necessary prior to multiple classification and conservation understanding are also discussed. (MS)