Effective environmental education (EE) is urgent as climate change and environmental degradation are proceeding. More theoretical models to enhance the effectiveness of environmental education are constantly presented, but a comprehensive view from teachers' perspectives is absent. This paper presents unique results from expert ENO Schoolnet Association's (ENO) expert EE teacher group interviews from the World Summit of Students for Climate Event (WSSC). These educators represent over 40 nations. The group interviews explore the teachers' perceptions of their students' environmental literacy and teaching of EE. The data were analyzed with content analysis. The results point out that these expert EE teachers feel that most students fail to achieve operational environmental literacy. This paper examines the potential school-related and student-related barriers preventing this operational literacy. Furthermore, the EE provided by the teachers usually lacks behavioral literacy methods. At the same time, the teachers feel that these methods should be emphasized to ensure the effectiveness of EE. In the future, it would be useful to study environmental clubs' potential to overcome some of the barriers and promote pro-environmental actions.