This text consists in a synthesis of the research in which I have been engaged for about fifteen years concerning the relationship between logic and mathematical reasoning, through the enlightening perspective offered by the model theoretic point of view due to Tarski. In a first part, I present the specific aspects of Model theory that I use in the didactic studies and I give an example of the relevance of this theoretical frame in order to deal with truth, validity, necessity and certainty. In the following parts, the analysis are developed according with three axis: the consideration of logical connectors beyond truth-value tables; some questions about the way mathematics teachers deal with quantification matters; the interpretation of m...