The purpose of this study is to investigate effect of project based learning method which is supported by prediction- observation- explanation (PBL supported by POE) method on attitude and behaviour towards environmental problems. The other aim of this study is to reveal experiment group students' views towards learning method. In this research called explanatory mixed method had been applied. In this study, Attitude Scale towards Environmental Problems, Behaviour Scale towards Environmental Problems and a semi-structured interview question are used as data collection tool. The findings obtained from the research show that there is a significant difference in favor of the experiment group among the point averages of the attitude and behavior posttest of the groups. When the findings regarding the questions posed to prospective teachers are examined, it is seen that prospective teachers explain that their attitudes towards environmental problems and behaviours aimed at preventing, eliminating those problems change positively after the application.