The error is often perceived as a disruptive element in the teaching/learning process. In communication teaching in a foreing language, more than in any other field, error disturbs. When a learner is mistaken, the teacher sometimes feels that he has failed in his mission. If the error disturbs, the fact remains that the teacher is confronted with it on a daily basis and must, if he considers it a problem, try to remedy it. Many language teachers consider the problem to be a matter for learners. Our experience has enabled us to realize that the teacher should, in order to best fulfil his function, question himself, take a step back from his practice and rely on solid theoretical knowledge in order to best adapt his Inter-vention at each teaching/learning situation. This article, focused on practice, proposes to retrace an experiment of research and reflection.