We report our progress on the "River Memorial Museum" didactic intervention project developed with schools, in the basin of the Atoyac River in Mexico, that are significantly impacted by the pollution produced through industrialisation. The teachers of the elementary schools in these communities, environmental scientists, educators, and community activists participated jointly in a "co-construction" process, designing "interdisciplinary" educational activities to study local environmental issues and recovering the principles of a "socio-critical perspective of mathematical modelling." In this paper, we centre on presenting the methodology of the didactic intervention with the teachers of one school of an Atoyac River basin community and the principles for designing educational activities we developed collaboratively with them. We believe this methodology could be helpful to support others in thinking about similar opportunities in their communities.