GlobalEd 2 (GE2) is a set of technology-mediated, problem-based learning (PBL) simulations for middle-grade students, that capitalises on the multidisciplinary nature of the social sciences as an expanded curricular space for students to learn and apply scientific literacies and concepts, while simultaneously also enriching their understanding of the social sciences. This paper reports the results of an implementation of the GE2 curriculum focused on water resources with 535 seventh and eighth grade students from both suburban and urban school systems. The results indicate positive changes in students' writing self-efficacy, interest in pursuing future science educational opportunities and the quality of their written scientific argumentation after participation in a GE2 simulation. Curricular implications and future research directions are discussed.