Mathematical and scientific knowledge are integral to preparing our population to be actively engaged and responsible citizens. Science and mathematics education, however, has mainly focused on concepts and skills detached from societal implications. In this paper we present an interdisciplinary international design research study in which we developed teaching and professional development materials connecting mathematics and science education to citizenship education. We outline the design research process, its theoretical basis as well as the design products. The study shows that it is indeed possible to develop such approaches supporting active citizenship and thereby the development of 21st century skills in mathematics education, thus strengthening the role of mathematics education in the STEM field.