Social dialogue is subject to many conditions which can be motivators or inhibitors of conversation. However, developing dialogue which can progress through the depths of ideas allows for a better understanding between the parties involved and an enrichment of individual ideas. This paper puts forward argumentation practice by means of verbal interaction in the science classroom as a means for building the student's knowledge. The evaluation of classroom discourse by means of three methods it is also put forward: identifying elements of three aspects - conceptual-cognitive, epistemic and social -, learning acts, and the pragma-dialectic rules. The analysis of a session is carried out, in order to postulate that the fulfillment of the rules of critical discussion proposed by the pragma-dialectics promotes argumentative development in the science classroom and in science learning.