Students’ difficulties in operating a graphics calculator

We investigated how students interpret linear and quadratic graphs on a graphics calculator screen. Clinical interviews were conducted with 25 Grade 10–11 students as they used graphics calculators to study graphs of straight lines and parabolas. Student errors were attributable to four main causes: a tendency to accept the graphic image uncritically, without attempting to relate it to other symbolic or numerical information; a poor understanding of the concept of scale; an inadequate grasp of accuracy and approximation; and a limited grasp of the processes used by the calculator to display graphs. Implications for teaching are discussed.