Diagrams in students’ proving activity in secondary school geometry

In this short paper, our focus is on how secondary school students work with diagrams during proving activity in geometry. Using data from a project investigating the design of dynamic geometry software (DGS) tasks that facilitate students’ proving activity, we found that the students’ discussion settled on various versions of the diagram. Out of six types of diagram that the students found, they concluded that their conjecture was not true for two of the cases. This underlines that the processes involved in using diagrams in mathematics are surprisingly complex, especially the extent to which students are aware of the general result or a specific diagram