This study aimed to develop pre-service science teachers' conceptual understanding of a nanoscience project through a newly introduced 8E learning cycle. This research was conducted during one semester of a nanoscience and nanotechnology course in the chemistry education department in Universitas Negeri Jakarta, Indonesia with thirty-three pre-service chemistry teachers. Data collection was carried out using classroom observation, in-depth interviews, reflective journals, and a chemistry test that explored pre-service teachers' conceptual understanding of nanoscience and nanotechnology. The 8E learning cycle consists of Engage, Explore, E-Search, Elaborate, Exchange, Extend, Evaluate, and Explain. The results show that the learning cycle engaged pre-service teachers in developing their conceptual understanding through collaboration, discussion, and reflection. The pre-service teachers understood the concepts of unique characteristics, physical properties, and chemical properties of nanomaterials. In each step of the 8E learning cycle, pre-service teachers reflected on and constructed their understanding within the principles of individual and social learning. The results showed that the 8E learning cycle can be used to develop pre-service teachers' conceptual understanding of nanoscience and nanotechnology and social skills.