Prospective Mathematics Teachers' Use of the Angle Tool in GeoGebra in a Geometric Construction Task

摘要

This case study investigates prospective middle school mathematics teachers' use of the Angle tool in GeoGebra, focusing on reflex angles in a geometric construction task. They constructed a parallelogram with individual heights for any two consecutive sides. We analyzed their screencasts to identify the ways in which they used reflex angles in GeoGebra. The results indicated that most participants concealed reflex angles in their geometric constructions. They most often showcased the ways in which reflex angles were eliminated utilizing software operations (e.g., keeping angles between 0° and 180°). Implications for future research are provided.