Although somewhat different from play, children's spontaneous activity can be seen as structured by a biologically given, adaptive, and natural learning system common to all human beings. Analysis of literature in which adults recall the play experiences of their early youth and careful analysis of young children's spontaneous activity reveal six consistent patterns of activity: children emerge as explorers, constructors, communicators, athletes, thespians, and creators of rituals. Through such activities as these, children learn much before entering educational or day care programs. Learning through spontaneous activity behaviors differs fundamentally from learning in school settings; contexts of spontaneous activity are open-ended and provide opportunities for further development, whereas curriculum-based learning is fixed and limited. Spontaneous activity skills can be used to supplement and complement school curriculum skills and activities at all age levels. Materials which best support young children's spontaneous activity are those which can be used "extensionally," or in many ways. The concluding discussion provides guides for identifying common characteristics of extensional materials as well as for using such materials, an example of spontaneous activity in the classroom, and a chart showing how particular spontaneous activities support learning in basic curriculum areas. (RH)