Artificial Intelligence (AI) tools are becoming integrated into the domains of teaching, learning, assessment and administration of educational institutions. While these advances are seen to provide opportunities, new concerns have arisen about the ethics of AI use. This has precipitated the publication of various AI ethics guidelines, however, the development of AI ethics policies for children and K-12 education has lagged behind. To contribute to the discourse on AI ethics and guide the direction of future curricula for schools, this article presents the findings of a systematic literature review in the ethics of AI within the context of K-12 education. From the analysis of 25 peer-reviewed studies published between 2010 and 2023, the authors map key themes and concerns relating to AI ethics in compulsory schooling. They also identify responses relating to the ethical use of AI, highlight research gaps and provide suggestions for future directions for researching AI ethics in K-12 education.