Previous studies have demonstrated that children use oral calculation procedures not
taught in school. The present study provided evidence for situational variables that
strongly influence the tendency to use such procedures. It also provided a qualitative
analysis of the oral mathematics used by Brazilian third graders. Concrete problem
situations were powerful elicitors of oral computation procedures, whereas computation
exercises tended to elicit school-learned computation algorithms. Oral computation
procedures involved the use of two reliably identifiable routines, decomposition and
repeated grouping, that revealed the children's solid understanding of the decimal system. In general, the children were far more successful in using oral mathematics than
written mathematics. An understanding of children's oral procedures may be useful in
developing more successful programs for elementary mathematics instruction.