Built Teaching French, Resisted at Home
Jean-Pol Martin developed the method systematically in the early 1980s while teaching French as a foreign language, and gave it theoretical grounding in several publications along with the German name it is still known by. It met resistance at first inside Germany's discipline-focused school system, an awkward fit for a method that hands over classroom authority to students, before it later spread widely through secondary schools and, by the 1990s, into universities as well.
In practice, material is divided into small units, and students work in groups of no more than three to work out how to teach a unit to their peers, adjusting their own teaching strategies while the classroom teacher stays actively involved, a structure distinguished from informal tutoring, which lacks this classroom structure, and from formal student teaching, which trains future teachers rather than working with a class's own students.