The paper presents the key elements of a model for in-service teachers training. An educational module about parabola as geometry object is the illustrative part of the model. The inclusion of dynamic geometry system applets allows some properties of the parabola to be established by examining dynamic constructions. Starting with the focus–directrix definition, the reflective property of the parabola has been proven and the equation of the parabola is worked out. A comprehensive comment on doubling-the-cube problem is given. Some directions for further development of the topic are pointed out.