Individuals influence the quality of the environment through their roles as citizens, investors, and members of organizations making choices that impact the environment. Yet, decision making regarding the environment, especially among young people, is not well understood. This study sought to describe the spontaneous decision-making process of 10-11 years old students, in the context of a sustainable residential neighborhood. The researchers aimed to understand how the students would spontaneously represent their decision-making process and the reasons that motivated their choices. Through their participation in a global simulation, the students were given fictitious identity, representing the future citizens of the residential neighborhood, and had to make decisions concerning the landscaping of their properties. The students’ reflexive journals and the researcher’s journal were the tools used to collect the data. In our results, we observed that the students used a variety of representations of their decision process (texts, schemata, lists, tables, drawings and plans) and a variety of decision modes : the compilation of similar advantages, the choice by elimination, the list of comparison of advantages and disadvantages, the choice based on compatibility of the options, the choice based on argumentation, the choice base on description, and the choice by visualization of the anticipated result. The students’ will of being surrounded by an environment that is visually pleasant and corresponds to their personal preferences are the main motivations behind their choices.