Critical thinking is at the heart of the latest educational policies. Yet if educational projects multiply, there still exist only very few scientific studies assessing the methods proposed by different stakeholders in education and training. These methods themselves in the norm do not build upon the existing scientific knowledge either. The present project aims at filling this gap by (1) designing and testing the first evidence-based critical thinking training for 8-14 year olds and, thanks to the complementarity of researchers and teachers of different disciplines (2) converging towards a more precise definition of critical thinking and providing a psychometric scale of critical thinking for French-speaking participants (3) testing the educational resources using this new scale in two stages (a qualitative pilot study, a quantitative large-scale study) (4) spreading these resources to institutions and teachers, as well as to the media and the general public.