Abstract
This paper tracks two children's mental strategies over a 5 year period (Years 2 to 6). Although
the children were students in traditional classrooms, where teacher-taught algorithms may
have conflicted with the children's spontaneous strategies, they continued to develop their
own efficient strategies throughout the period of the longitudinal study. However, by Year 6,
both children were also employing taught pen and paper algorithms which were less effective
for mental calculations. Finally, some implications for teaching are discussed.
Ann Heirdsfield
MENTAL ADDITION AND SUBTRACTION STRATEGIES: TWO CASE STUDIES