Enhancing teachers' knowledge of students' thinking: The case of graphics calculator graphs

Year: 2005

Author: Cavanagh, Michael

Type of paper: Refereed paper

Graphics calculators are widely available in Australian schools, particularly as a tool for drawing and interpreting graphs in mathematics instruction. There is much research on pedagogical practices associated with graphics calculators, but relatively little on the design of professional development programs on the use of graphics calculators. What calculator knowledge do teachers need? And would informing teachers about how students interpret the graphics calculator display lead to better student outcomes?

This paper reports on a graphics calculator in-service program based on the principles of Cognitively Guided Instruction (CGI). A series of clinical interviews identified student misconceptions associated with interpreting straight-line graphs and parabolas on a graphics calculator. Interview results were reported to teachers during a two-day workshop. Teachers were subsequently observed using graphics calculators in the classroom and students from these classes were interviewed using the original protocols.

Results show that the CGI intervention was largely successful. Teachers reported greater confidence in using the technology in the classroom and dealt with a wide variety of examples that confronted student misconceptions. Students from the observed classes performed significantly better than the control group on tasks that required them to interpret graphical images on the graphics calculator screen.