The history of Australian mass schooling has seen contestations over school and curriculum purposes, zig-zagging across conservative and progressive directions. In this paper, we examine how possibilities for students to have 'voice', 'participation' and 'leadership' in their learning are currently limited in Australia. Policy framings, we argue, dampen potentials for connecting young people's democratic and activist impulses -- manifest, in our example, in the Schools Strike for Climate movement -- with curriculum activity that responds to local-global challenges such as the viral-ecological crisis. We propose an activist curriculum praxis wherein young people undertake action-research -- in collaboration with diverse community actors, teachers and academics -- on "problems that matter" for local-global future life with others. Since local-global emerg"encies" are emerg"ent", curriculum must build citizen-capacities to work together, apprenticing to problems that matter for social futures, creating emergently needed knowledge-in-action. This participatory-democratic curriculum approach challenges schools to become more socially just and proactive institutions.