Citizen science fosters collaboration between researchers and the public, bridging educational research and practice. While commonly associated with natural sciences and environmental monitoring, its application also spans other fields. Hybrid.Learning.Spaces@School is a citizen science project in technology-enhanced learning (TEL), where researchers, teachers, students, and business partners co-design hybrid learning scenarios for vocational secondary education. Hybrid learning, a key innovation in TEL, combines on-site and remote instruction simultaneously to expand educational access. Running from September 2024 to August 2027, the project uses a design-based research approach to explore success factors for hybrid learning. This paper presents findings from the first co-design iteration, including a large-scale project day at the university with over 100 participants, followed by co-design workshops at four schools. The project day allowed stakeholders to discuss the challenges and opportunities of hybrid learning, focusing on technological, pedagogical, social and organizational factors. Research questions and initial solutions were developed. The co-design workshops facilitated the creation of concrete hybrid learning scenarios tailored to stakeholder needs and laid the foundation for evaluation concepts. This paper discusses stakeholders’ participation, research methods, and their reactions to the co-design process. These findings inform the next phase, where the hybrid learning scenarios will be implemented in classrooms and evaluated using both qualitative and quantitative methods. Ultimately, the project aims to provide evidence-based recommendations for effectively integrating hybrid learning in vocational education.