This article discusses how the key players' multilayered collaboration may be enacted by the Change Laboratory methodology in the footsteps of Virkkunen and Newnham (2013) to address a complex issue for the benefit of adolescents. It can be defined as a group processing approach used by a group to solve a problem of its own defining. Over six months, members of a school community played an important role in participating in the modelling of classroom lessons with adolescents facing the new guidelines of the Canadian Cannabis Act in 2018. Drawing on the theory of expansive learning and the cultural-historical activity theory (CHAT), we used the Change Laboratory approach to dialogue on the problems and solutions to be implemented. The results examine specifically how some of the school community members contributed to the co-modelling of these lessons, taking into account the adolescents' needs in two schools. The collaboration between the members evolved over time. The vertical power hierarchy usually present in schools was modified as parents, grandparents, a medical doctor, a special education teacher, two teachers, and five students agreed to sit together to address the health issue. The qualitative analysis brings to light how the participants shared their needs and engaged in taking transformative actions to intervene directly in two high school classrooms.