Christian Rütten examines in his study what concepts elementary school children have regarding negative numbers before they are addressed in the classroom, and how these relate to academic perspectives such as number line or equivalence class models. The research framework is based on the model of didactic reconstruction, focusing on three central investigative tasks: academic clarification, capturing the learner's perspective, and didactic structuring. To capture the learner's perspective, the author explores psychological and mathematics didactic viewpoints and situates the learner's perspective within the cognitive layer structure. He places particular importance on metaphors as cognitive structures and accordingly develops a reconstructive metaphor analysis as a method of evaluation. An empirical study involving over 500 elementary school children reveals a wide spectrum of understanding.