Die Mittelsenkrechte – stoffdidaktische Analyse und Bezüge zum Unterricht

The concept of the perpendicular bisector is analysed with a didactical view and different opportunities of definitions are discussed. After that we focus on the implementation in the classroom. Therefore, we look at the definition used in schoolbook but also the previous knowledge of children around the perpendicular bisector. Finally, written explanations of seventh-graders show how they argue with the concept of the perpendicular bisector. Classification: D70, E50, U20. Keywords: geometry, perpendicular bisector, mathematics education.