This paper reports on a study of learners' use of immersive spatial diagrams to make arguments about three-dimensional geometric figures. Immersive spatial diagrams allow learners to use the movement of their bodies to control their point of view, while immersed in three-dimensional digital renderings. We present analysis of two pairs of pre-service elementary teachers' argumentation about the shearing of pyramids, using the ck¢-enriched Toulmin Model of Argumentation (Pedemonte & Balacheff, 2016) to link the affordances of immersive spatial diagrams to the learners' mathematical reasoning. We share how one pair of learners took points of view bending beside and standing within the pyramid to describe how the space inside is transformed without reference to one- or two-dimensional components of the representation. [For the complete proceedings, see ED630060.]