This study aims to present a sample online STEM education design that can be used at secondary school level. In the exemplary design, "environmental issues" were used with a focus on how important it is that the students approach the problems from an ecological perspective. The study was carried out with the "action research" pattern, in which each cycle feeds each other. The study group consist of 11 students in the 6th grade. The action research, which was completed in two cycles, lasted a total of 10 weeks. The data, collected by qualitative means, were analyzed through "descriptive analysis" and "content analysis". At the end of the study, suggestions were made for the development and implementation of lesson activity to be used for online STEM education. It has been concluded that the in-class (synchronous) and extra-curricular (asynchronous) parts of the activity are included in the activity and it is carried out through learning management systems like Padlet. It is important to include activities that employ social and emotional skills in the prepared content. Digital panel tools or instant communication applications are used for the continuity of communication. In addition, the course materials used were prepared with tools like Teachermade so that the teacher can give interactive feedback.