This article deals with present problems of technology integration in teaching mathematics, especially at the secondary level. The first part is focused on the role of the teacher in teaching supported by digital technology and on his knowledge needed for developing pupils' understanding and skills.
The second part is concerned with technology integration from the pupils' learning point of view, with the emphasis on pupils' knowledge needed for effective using technology in mathematics. The examples illustrating discovering and testing hypotheses in dynamic geometry Geogebra are included.