In today's world, we are more and more faced with a multilingual audience. In an academic background, teaching languages has to adapt to this evolution. From the presentation of a school with international classes and a study of the situations of different groups of learners (German speakers, French speakers, bi-lingual and multilingual speakers) and considering specific errors made by each group, some tendencies regarding the frequency of these errors can be noticed. A detailed analysis of spelling, morphological, semantics and syntactical mistakes can help improve and go deeper into the understanding of learning processes. We can notice similarities as well as differences as far as the types of errors and their frequencies are concerned, according to the age and the part played by languages. Among the different learners, the results and the conclusions should lead to a change of attitude in front of these errors. By thus considering the learner as the core of the discussions and thoughts, the didactical and pedagogical approaches should evolve. Some examples of pedagogical units based on a contrasted approach concretely illustrate the teaching opportunities in a multilingual background. By making teaching more motivating, by supporting all students, by taking their skills into account and by favouring their critical intercourse and intercultural capacities, such an approach meets the requirements of today's society.
