Contribution: This article presents a systematic literature review of research concerning cyber security education for children (under 18s) on a global scale. Background: While the Internet brings great convenience to children, it can potentially cause harms due to lack of knowledge about online risks. Research Questions: 1. What cyber security skills are taught to children worldwide? 2. What are key strategies/methods for cyber security education? 3. What stakeholders are regarded as responsible for cyber security education of children? Methodology: Using the PRISMA protocol for literature search, 412 papers published between January 2015 and June 2021 were retrieved and 44 were identified for thematic analysis. Findings: The content considered for cyber security education varies greatly between nations, being therefore inconsistent and filled with gaps. This article suggests curriculum content framed around six broad categories of cyber security awareness for educators and policy makers to follow, and further recommends that curriculum should be influenced not only by expert advice, but also through a "bottom-up" approach listening to children's voice to adequately gauge the level of Internet engagement and their activities. This article finds that innovative teaching methods (e.g., gamification) are claimed to provide "hands on" and "real life" experiences that greatly enhance traditional classroom teaching (e.g., mentoring), but existing literature lacks evaluation of comparative effectiveness. Finally, this article finds that the primary provider for cyber security education, from the sample analyzed, is regarded as schoolteachers, supported by parents and by a formal curriculum resourced adequately by governments.