Abstract
If the ability to reason proportionally seems to be a good indication of likely success in
further mathematical pursuits (Lamon, 1999), how do children develop this ability, and
how can teachers facilitate this? In this present study, six ratio/rates task-based assessment
questions were trialled on ten students from Grades 5 to 9 in an attempt to describe the
developing understanding of students within this construct of rational number. Tentative
points of growth (or stages of understanding) are suggested, with some implications for the
classroom teacher.