Science education has changed in recent decades with respect to key issues faced in this century. These issues such as renewable energy, waste management, air quality, and biodiversity require dealing with the transition toward a sustainable future. Thus, to contribute to the reconceptualization of science education in a developing country, the present study aimed to assess (1) Turkish middle school students' environmentally responsible behaviors, nature relatedness (NR), and motive concerns and (2) the power of environmental motive concerns, and NR in predicting the related behaviors. Measuring tools covering the NR scale, the environmental motive concerns, and children's responsible environmental behavior scale were administered to middle school students in the Northern part of Turkey. The results indicated that these students reflected an external nature-related worldview. Regarding their behaviors, it was revealed that the students frequently engaged in some actions linked to physical and economic contribution to the environmental quality. However, they did not demonstrate any actions on political commitment although they were very concerned about the environmental issues. Examining the predictors of their responsible environmental behaviors, a linear combination of these attributes significantly contributed to explaining such behaviors. This study provided practical tips for science and sustainability educators in that children could be provided with some opportunities to get in touch with nature and appreciate the value of being in nature.