Foreign languages and mother tongues for language appropriation

In this book, I propose a method of articulating the foreign language and the mother tongue to smooth out the many difficulties associated with learning foreign languages, especially French. It's a method I've tried and tested myself over more than two decades. When asked about the use of the mother tongue in their lessons, many teachers say that it can be justified for a number of reasons: to re-establish a semblance of communication with learners during the lesson, to explain the tasks to be carried out during the lesson, the exercises, the assessment, to make instructions explicit, to exemplify situations that are difficult to implement, to make progress in the program, to avoid wasting time... This method comes at just the right moment to respond to a concern that often hinders foreign language teachers: how to use the mother tongue in a way that helps learners to better follow the lessons and move forward in the process of appropriating these languages?