This research presents a qualitative case study that investigates the biology and preschool student teachers' and teachers' experiences of online teaching during the Covid-19 pandemic. The study utilizes the diffusion of innovations theory to understand the adoption and application of online teaching as an innovation. The participants in the study consisted of eight senior biology teachers, four biology teachers, nine senior preschool education student teachers, and three preschool teachers. Data collection was conducted through online surveys administered to the participants at the end of the 2021 school year. Additionally, the researchers, who also served as student teachers' supervisors, took observation notes during the online teaching practice to complement the survey data. The findings of the study reveal insights into the adoption of online teaching and learning processes as an innovation among teachers and student teachers. Analysis of the participants' responses regarding their readiness and experiences indicates that student teachers exhibit higher levels of perception in adopting and applying online teaching compared to the teachers. Interestingly, the experiences of the participants from different fields did not significantly differ in terms of adopting the innovation. This study emphasizes the need to increase the relative advantages of online teaching, minimize its complexity, and be prepared for similar situations. Incorporating online lesson planning and management courses in teacher education programs and providing in-service training can enhance educators' knowledge and experiences in online teaching, contributing to the adoption of online education as an innovation. Additionally, further research is needed to explore the role of parents in online learning environments. Engaging stakeholders from various fields will provide valuable data for a deeper understanding of online teaching and learning.