Abstract
Numerical magnitude is often represented along a spatial continuum known as the mental number line, with magnitudes increasing from left to right. Cross-cultural studies indicate that reading direction influences the orientation of these spatial numerical mappings, while developmental research suggests that formal schooling plays a crucial role in promoting more precise number line representations. This paper reviews how reading direction and education shape spatial-numerical associations, discusses implications for future research and highlights the need to understand the connections between the mental number lines, number sense and learning mathematics.