A research gap exists with regard to the analysis of school children and adolescents' awareness on environmental issues. Current investigation analyzes data of 240 children and adolescents, aged between 8 and 14 years, within different school contexts in the mid-southern region of Brazil, on their knowledge level and moral judgment on solid wastes, river water and tree life. Whereas the exploratory research with different groups of different ages verifies the manner behavior emerges and changes, the transversal design gives an evolution aspect of data through the examination of a great number of agents. Results showed that children and adolescents have similar knowledge on the environment within different school contexts, except differences at environmental knowledge level. The latter revealed a mild broadening trend in proportion to the 8-14 years age bracket. Environmental moral judgment varied a lot, regardless of the agents' age, and failed to be related to the knowledge that children and adolescents had on the environmental themes. Schools featuring well-defined pedagogical proposals were positively salient among the others. Environmental knowledge and moral judgment on environmental issues are not determining but implied chiefly as from the age of eleven, since both are the result of the agents' social interactivity within the environment and basically require affectivity and cooperation.