Evgenios Avgerinos & Andreas MarinosOn Using a Dynamic Geometry Software in the Comprehension of the Similarity of Triangles

Grozio Stanilov & Slavka SlavovaModels of the Real Projective Plane and Linear Combination of them

Hiroshi OkumuraGeneralized Non-Archimedean Twin Circles of the Arbelos

Ivanka Marasheva-Delinova & Emil Delinov Motivation of Students for Research Work Using Rotation Bodies Geometry

Kliment Vassilev & Donka PashkulevaOn the Concept of a Quadrilateral in the School Geometry Course

Masayuki WatanabeCircumscribed and Orthogonal Archimedean Circles in Generalized Arbelos

Sava Grozdev & Toni ChehlarovaCongruences in Triangular Nets

Stavroula Patsiomitou & Anastassios EmvalotisDeveloping Geometric Thinking Skills Through Dynamic Diagram Transformations

Toni Chehlarova & Evgenia SendovaExplorations with Rotational Solids