Our integrative and highly innovative policy measure directly addresses priority 1. It supports maths and science teachers (hereafter called science teachers) to deliver inclusive education for all students, build active citizenship and foster intercultural learning. Our measure connects science education to promoting fundamental values and intercultural learning. Its core is a well-researched teaching approach, inquiry-based learning, that we expand to support combatting underachievement, in particular of learners from low socio-economic backgrounds and migrant families, and to promote a modern vision of science including social, cultural and ethical dimensions. To support teachers adopting the approach, we will design a state-of-the art professional development (PD) toolkit based on research and deliver related PD courses. An important feature of our proposal is unparalleled tandems: In each country Ministries of Education to lead the policy experimentation measure and set the frame for implementation are paired with university experts to conceptualise and deliver science teacher PD. An internationally renowned research institution will evaluate the field trials: A multi-method evaluation design with quantitative and qualitative data accompanies the process (pre-post control group design triangulated with case studies). This ensures reliable, valid conclusions on our measure’s effects and routes to up-scaling. Project coordination by a team highly experienced in managing large-scale international projects, together with the outstanding project team will ensure highest-quality delivery, largest possible impact and routes to scaling-up. Our measure fully contributes to ET2020, the Youth Report, the Paris Declaration aims and related national policies. It combats underachievement; links science, social and civil competences; and effectively supports teachers to deal with increased social, cultural and competence-related diversity in their classrooms.