Abstract
Spatial reasoning has been known to have a solid connection to mathematics achievement and the mental mechanism underlying embodied mathematics. However, how spatial reasoning mediates the process of mathematising mathematical ideas is still being investigated. Therefore, this article aims to elaborate on using number lines as a spatial tool to promote spatial reasoning and mathematical understanding. The case is discussed from the perspective of the embodied cognition theory and the instrumentation theory. Based on the theories, the idea of spatialised instrumentation is promoted to explain the nature of spatial reasoning in promoting embodied mathematics learning through spatial learning tools. Under spatialised instrumentation, it is argued that spatial learning tools such as number lines can be used to promote meaningful embodied mathematical experiences involving spatial reasoning that potentially foster the development of mathematical understanding. This finding contributes to the effort of spatialising mathematic learning.