Through didactic discourse we understand the set of processes through which the exchange of meanings between teacher and students in a certain educational situation is carried out. We can talk about didactic discourse in terms of influence or action taken in order to provoke changes in the personality of the student. For the understanding to occur, the discourse must be organized by virtue of some communication laws. Oswald Ducrot (1996) establishes such laws: 1. The law of sincerity, with three requirements - to say only what is true, to prevent the auditor otherwise and not to speak in the absence of competence in that field; 2. The law of interest - with the requirement to talk to the other only about what interests him; 3. Informational law - which means not giving anyone the information they have; 4. The law of completeness - with the requirement to indicate the exact extension of the facts presented, no more, no less; 5. The litote law - says less than you know from modesty, artifice or consideration, without the intention to deceive the interlocutor. For an effective communication between teacher and student, the atmosphere in the classroom must be favorable, and for this we must take into account the emotional universe of the participants in the communication. The didactic discourse is the transmission of information from one person to another for educational purposes. The didactic discourse it is more an oral, interactive speech. From Peirce's perspective, semiotics is the instrument of education, as a representation in terms of continuous action, process. To educate means to inform and to form. The education is reduced to the transmission of knowledge on the background of a "truncated semiosis" in which the recipient plays a passive role. A behaviorist (stimulus-response) relationship is established, schematized as follows: O (knowledge of the educator) → R (expression of this knowledge) → I (receiving the expression of knowledge). Effective education can not take place without the emotional involvement of both the teacher and the student. Rhetorical elements are summed up when teaching persuasion, which is a process of guiding people to adopt ideas, attitudes or actions (rational or less rational). Persuasion is based on discussion and "attractiveness of presentation" instead of using means of force. Thus, over the centuries, the most powerful of the calls to consciousness has been considered, although this opinion of persuasion is rarely mentioned in the power of emotion to influence the mind and the way knowledge is accumulated.