At a time marked by the public concerns about societal and environmental implications of technoscientific innovations, the purpose of science education is to prepare citizens to take active part on society choices. The generalisation of Education for Sustainable Development signs the integration of world contemporary stakes in problematized Scientific teaching while Inquiry Based Science Education penetrates curriculums of all countries. In such a context, the teaching of Socially Acute Questions (SAQs) incorporates uncertainty and complexity at the heart of the teaching and learning process. Environmental SAQs call for expertises that take stock of socio-ecological interactions at different scales, political and technoscientifical options, interests and values at play, connections between debated problems. At a crossroads of SAQs’ didactics and digital pedagogy, this thesis aims to document forms of collective learning of democratic involvement in citizen expertises of Environmental SAQs. We make use of Digital Work Environment potential to broaden community of learning beyond geographical boundaries and disciplinary compartmentalization. We scrutinize collective SocioScientific and Sustainability Reasoning (S3R) of students in their fourth year of a teacher education degree from different disciplines and Universities in France and Australia. The originality of this work lies in seeing together Socio-Discursive Interactions and improvements of S3R collectively built. It reveals the major interest of socio-epistemologic disturbance occasionned by cross-cultural meetings.