The aim of this paper is to create two interactive electronic materials for teaching geometrical optics, especially imaging on thin lenses. Geogebra mathematical dynamic geometry software is employed for preparing the interactive constructions. In this software it is possible to work both in online mode and after installation in offline mode. There are constructs created for the software for mathematics and physics that can be used by the teacher. The paper does not describe a detailed procedure for preparing both constructions, and as an appendix we attach the original procedure for the construction as exported by the software. The reader is also introduced to the basics of geometrical optics, especially imaging on thin lenses. The values of parameters a, á and f that are measured directly by the created construction will be compared in the results with the results of these parameters, which are obtained from the derived rendering equation. In this way, we will confirm the correct function of the interactive constructions that have been created. The conclusion of the paper summarises the advantages and disadvantages of the created teaching materials.