MultiMedia Mechnologies are opening enormous possibilities for education. They allow to eliminate time and space constraints and so they allow to transfer knowledge and information, to interact on line in real time, to recreate something that was desappeared, to personalize learning programs and so on. MMT foster teaching activities either on site and on line, leveraging the specific learning process of each learner. Effectiveness of MMT in learning on site arises when we consider the use of images, sounds, written words in hiper-text; effectiveness of MMT in learning on line arises from the importance of interaction among people, since learning process is a social process of common building of meaning.