Understanding of Earth's systems, including the crucial role of human beings within them, is an important part of citizens' ability to think intelligently and critically about the environment, pollution, sustainability and other socio-economic and scientific issues central to life in the modern world. Part of this understanding involves seeing the world as an integrated whole in which what happens in diverse places in the world may be equally relevant for students' lives. In this regard, it makes sense to study both remote and local environments within the system thinking approach--where such distinctions naturally become blurred. The present research, accordingly, focuses on a study unit entitled "Life at the Poles" and investigates the development of junior high school students' understanding of Earth systems and their level of conceptual complexity as a result of participating in it. The "Life at the Poles" unit is based on the "explanatory story" approach where one central theme is used as a focal point for an interdisciplinary study of certain natural phenomena, in this case, the possibility of life under the extreme conditions at the poles. Concept maps and Likert-type questionnaires were employed as research tools, allowing the collected data to be analyzed both qualitatively and quantitatively. The research findings indicate that the students significantly improved their Earth systems understanding and, importantly, greatly increased their awareness of human beings' influence on the environment, including remote environments such as the pole.