This deliverable is a comprehensive guide aimed at empowering teachers across Europe to integrate Citizen Science into their classrooms, offering both theoretical insights and practical applications. Citizen science, the practice of engaging the public in scientific research, serves as a dynamic pedagogical tool to foster inquiry-based learning, critical thinking, and active participation among pupils. This resource outlines the principles of Citizen Science, its alignment with educational frameworks, and its potential to make learning more engaging and relevant. Teachers will learn how to incorporate Citizen Science activities into their curricula, leveraging real-world data collection and analysis to bridge the gap between classroom theory and global scientific challenges. Practical examples of Citizen Science projects suitable for children are given. By participating in Citizen Science projects, pupils not only enhance their STEAM skills but also develop a deeper sense of social responsibility and global awareness.