This dissertation explores the design and implementation of a web-based mapping system tailored for primary school children in London, as part of the "Little Investigators" project. The system allows young users to identify, annotate, and share local landmarks, enhancing their spatial literacy and community engagement. Utilising open-source technologies like HTML5, CSS3, JavaScript, PHP, MySQL, and Leaflet.js, the platform focuses on creating an intuitive user interface, ensuring robust data security, and maintaining accessibility across various devices. The research includes comprehensive literature review that places the project within the broader context of educational mapping and participatory GIS, emphasising the need for child-centric digital mapping solutions. The project methodology is based on an iterative design process, adapting to challenges such as limited access to advanced APIs and addressing significant literature gaps. The dissertation underscores the potential of digital mapping tools in educational settings and suggests further refinement and planning to enhance the system's educational impact.