The rapid and ongoing technological developments and the changes in societal practices require us to update our understanding and skills relating to digital technology use continuously. Various frameworks have been created in recent years to explore the different aspects of "digital literacies" or "digital competencies" and a range of newer concepts and dimensions have emerged in the literature aiming to capture the complexity of digital engagement. The main aim of this systematic literature review (SLR) was to map out which elements or issues of "critical digital literacies" (CDL) relevant for school education currently feature in the academic literature and international policy documents. The secondary aim was to use the findings of the SLR to inform the creation of a research-based framework for school education. The review process followed a systematic protocol for answering specific research questions. Research articles were sought in two electronic databases--EBSCO (Academic Search Complete) and Web of Science--and policy documents were sought on the Internet using Google search. A total of 139 research articles and policy-related documents were used for the analysis. The main dimensions based on the analysis were the following (in the order of most hits): E-safety, Participation and presence, Digital literacy, Media literacy, Digital citizenship, Technology literacy, Information literacy, Data literacy, Digital game literacy, Online learning, Digital creativity and innovation, and Digital well-being. The emphasis in the research articles was on negative issues, although publications also outlined several positive issues about digitality. The emphases of the research articles and policy-related documents differed somewhat. The findings of this SLR have implications for researchers, policy makers and educators interested in the changing nature of critical digital literacies and the dimensions and subdimensions relevant for school education.