Combining mathematics and environmental issues may be a valuable way not only to increase environmental awareness of students but also provide real life context to the mathematics lessons. In this study, it was aimed to explore changes in the views of 5th grade students toward sustainability with the help of the tasks integrating environmental education and mathematics education contents. Based on this aim, as convenient sample, a fifth-grade classroom in a private school in Tukey selected and students attending to this classroom participated in the study. Environmental education issues and mathematical contents were integrated in students' tasks and these developed tasks were applied as a regular part of the teaching processes of this classroom. Before and after applications, semi structured pre-interviews were carried out with nine students randomly selected from the classroom and the data obtained from these interviews and researcher teacher's observations were analyzed qualitatively. The findings as the changes in students' views were combined under 3 categories; students' views about environmental problems; students' own individualized role in environmental problems and students' views towards integration of environmental education and mathematics. This study may provide valuable contributions both to the mathematics education and science education fields in this regard.