In the digital and infodemic age, the battle against ready-made beliefs, manipulation, cognitive biases, intellectual slowness, etc., is a crucial issue for our society. This challenge is not only intellectual, but also ethical and social, and constitutes an essential component of education for citizenship. For several years, many cultural and educational actors (first and foremost, the Ministry of National Education) have taken up this societal challenge, by proposing initiatives to educate in critical thinking, often in close connection with media education. However, the question arises as to the impact of these initiatives. There is a pressing need to understand and know what works and what does not work in these initiatives. The OPTIMIST project focuses on four dissemination devices for critical thinking skills, set up by academics, a CCSTI (the Quai des Savoirs) and a CSTI association (Science Animation) for schoolchildren (middle and high school students) and citizens, at the level of the Toulouse academy. The ambition of the project is threefold: (i) to set up a rigorous experimental methodology to evaluate the impact of these devices on a sample of several thousand people (mainly secondary school students), (ii) to start from the scientific knowledge acquired over the last few years, in order to evaluate critical thinking longitudinally, and (iii) to assess the weaknesses and benefits of the four dissemination devices in order to propose new actions to provide critical thinking tools, but also to make available to all the actors a valid critical thinking evaluation test