Jean-Pol Martin
Martin was born in 1943 in Paris and went to Germany in 1968.  He studied German and French in order to become a teacher at a German grammar school, becoming a professor for foreign language teaching didactics at the Catholic University of Eichstätt-Ingolstadt (Bavaria) in 1980.  In that year he had the idea to let the students teach their peers in French.  That experience was successful, so he could establish the "Lernen durch Lehren" (LdL) (learning by teaching) method in Germany.  He was the first scholar to do active research on that topic for 25 years, building a wide network with several thousand teachers and promoting it to a large scale.  All teachers in Germany are trained in that method during their pedagogic studies.