In this study, a learning unit on microorganisms for ninth-grade students was developed based on the Science-Technology-Environment-Society (STES) approach. The learning unit contained 15 learning tasks, which were performed in individual and cooperative learning settings, using a variety of teaching/learning methods with an emphasis on the interdisciplinary approach. The study goals were to investigate the impact of the learning unit on ninth-grade students' cognitive and meta-cognitive domains and attitudes toward peace. The sample included 91 students from two classes in villages A and B, and one class of gifted students in Arab schools in the north of Israel. The unit enabled the evaluation of the learning process through students' portfolios, semi-built-in interviews, and closed questionnaires toward environment and peace. Both, quantitative and the qualitative analyses were used. The portfolio content analysis showed a significant improvement on the cognitive and meta-cognitive knowledge of the students, including asking questions, higher order cognitive skills, argumentation skills, self-evaluation and reflection. Triangulation of data assured the high reliability of the results, which revealed a significant improvement in attitudes toward environment and peace. We therefore suggest developing the concept STES to STEPS: Science-Technology-Environment-Peace-Society.