Classification: E33 G43 G33 C33

Keywords: Logical Thinking; Geometry; Abstract Reasoning; Geometry; Flaeche; Perimeter; Cognitive Development; Lower Secondary; Triangles; Plane Geometry; Elementary Geometry; ; Logisches Denken; Geometrie; Abstraktes Denken; Geometrie; Flaeche; Umfang; Kognitive Entwicklung; Sekundarstufe 1; Dreieck; Ebene Geometrie; Elementare Geometrie