A constructivist interpretation of the learning process has been supported by research on students conceptions in physiscs in the last twenty years. The paper outlines the elements of a constructivist view of learning referring to knowledge as a personal construction, which is bound by viability criteria, not by the non operational notion of an objective reality. Conceptual change is, or should be, the objective of instruction. Computer technology can be used in education to establish a constructive environment, which would help students by providing a new understanding of the world.