“…Although there have been other child development theories, such as those of Jerome Bruner (see Bruner, 1960), Jean Piaget's work has had the most signi cant in uence on beliefs about what mathematical ideas were considered appropriate for children of different ages (Young-Loveridge, 1987). Piaget's (1990) basic premise was that children progressed through: four great stages, or four great periods, in the development of intelligence: rst, the sensori-motor period before the appearance of language; second, the period from about two to seven years of age, the pre-operational which precedes real operations; third, the period of concrete operations (which refers to concrete objects); and nally after twelve years of age, the period of formal operations, or propositional operations.…”