Educational researchers are showing a growing interest in Participatory Design (PD) and other collaborative co-design approaches. This paper considers the ways in which education researchers considering PD can benefit from drawing on the approach's heritage in the 1970s' Scandinavian 'cooperative inquiry' tradition. In particular, the paper highlights four core principles from the Scandinavian tradition, i.e.: the pursuit of socio-ethical outcomes, sustained consideration of what constitutes 'participation' and 'practice', and PD as a design process. While positioning these principles in school-based research is not easy, the paper considers how this has been achieved within the field of child-computer-interaction -- an area of research that is also often conducted with children in educational institutions. While remaining mindful of the institutional constraints of school-based research, we argue that these Scandinavian principles can be borrowed and built upon by educational researchers -- thereby extending the scope and ambitions of educational PD research.