This article presents a model for the development of an environmentally oriented unit designed to be implemented as an integral part of the science core curriculum. The program's main goal is encouraging students at the junior high-school level to develop systems-thinking and environmental insight as a basis for environmental literacy. A design-based research was employed in order to construct the learning program and improve it in consecutive cycles. The findings indicate that junior high school students who were involved in the learning process--through knowledge integration activities, scientific inquiry, and outdoor learning--achieved a meaningful improvement of their cyclic and systemic understanding of the water cycle. The article concludes with a summary of the program's design elements we recommend using in other programs seeking to foster students' understanding of natural cycles within the context of their influence on people's daily lives, rather than in the isolation of their specific scientific domains. It is suggested that an environmentally based science curriculum should involve authentic, real environmental topics, and at the same time, it should emphasize the role of scientific knowledge and skills that are needed for the development of environmental literacy. (Contains 3 tables and 5 figures.)