Background: People of all ages are flooded with health claims about treatment effects (benefits and harms of treatments). Many of these are not reliable, and many people lack skills to assess their reliability. Primary school is the ideal time to begin to teach these skills, to lay a foundation for continued learning and enable children to make well-informed health choices, as they grow older. However, these skills are rarely being taught and yet there are no rigorously developed and evaluated resources for teaching these skills.Objectives: To develop the Informed Health Choices (IHC) resources (for learning and teaching people to assess claims about the effects of treatments) for primary school children and teachers.Methods: We prototyped, piloted, and user-tested resources in four settings that included Uganda, Kenya, Rwanda, and Norway. We employed a user-centred approach to designing IHC resources which entailed multiple iterative cycles of development (determining content scope, generating ideas, prototyping, testing, analysing and refining) based on continuous close collaboration with teachers and children. Results: We identified 24 Key Concepts that are important for children to learn. We developed a comic book and a separate exercise book to introduce and explain the Key Concepts to the children, combining lessons with exercises and classroom activities. We developed a teachers' guide to supplement the resources for children. Conclusion: By employing a user-centred approach to designing resources to teach primary children to think critically about treatment claims and choices, we developed learning resources that end users experienced as useful, easy to use and well-suited to use in diverse classroom settings.