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Children and arithmetic.

The development of children's understanding of mathematical relations and of their grasp of the number system is described. It is discussed that children easily recognise one-way part-part relations but that the number system at first causes them difficulty. Children's relational understanding allows them to solve addition and subtraction problems fairly well when these deal with simple increases and decreases in quantity. It also helps them to make proportional judgements when these involve part-part relations. However, problems that involve relations between parts and wholes are at first extremely difficult. The review also deals with the effects of context and shows the considerable aptitudes that are handed on to children in informal settings.