Early childhood years were believed to be a precious time to implement Science, Technology, Engineering, and Mathematics (STEM) education activities. Children can practice STEM-related skills and form their initial ideas about STEM professions. In this research, we aim to present an integrated STEM education curriculum for early childhood teachers, based on an engineering theme. We collected qualitative data through teachers' self-evaluation forms and reflective journals. Seven teachers implemented the curriculum with the participation of 105 children. Teachers mostly expected improvement in cognitive process outcomes before the implementation. Children's first reactions to the curriculum were curiosity and excitement. Cognitive process and social product outcomes were detailed and varied during and after the implementation of the curriculum. Teachers collaborated with their colleagues to plan and overcome the difficulties they encountered. The presented curriculum was found to be appropriate for implementation in early childhood settings. Further research was suggested to focus on the impact of the curriculum on children's skills.