Environmental education is a key strategy for enhancing environmental literacy and achieving the Sustainable Development Goals (SDGs). This study evaluated the environmental awareness of 229 secondary school students in Kashmar, Iran, with a focus on ecosystem protection and waste management. Data were collected using an 18-item Environmental Awareness Questionnaire with confirmed validity and high reliability (Cronbach's α = 0.850) and analyzed using descriptive statistics and one-way ANOVA. The findings revealed a moderate overall level of environmental awareness (2.61 ± 0.54). Students demonstrated greater awareness of ecosystem protection (2.71 ± 0.72) than waste management (2.52 ± 0.56). Although 11th- and 12th-grade students had slightly higher mean scores than 10th-grade students, these differences were not statistically significant (P > 0.05). The results indicate that while students possess a reasonable understanding of general environmental issues, their knowledge of practical waste management practices, such as waste separation, recycling, and waste reduction, remains limited. The absence of significant differences across grade levels further suggests that progression through school alone does not substantially improve environmental awareness. The findings highlight the need to strengthen environmental education through experiential, skills-based, and practice-oriented learning approaches, particularly in waste management. Such improvements can enhance environmental literacy, promote responsible environmental behavior, and contribute to the achievement of SDG 4 (Quality Education), SDG 12 (Responsible Consumption and Production), SDG 13 (Climate Action), and SDG 15 (Life on Land).