Mathematics in Australia specifies spatial reasoning as a general capability within the curriculum. However, psychological research to date limits spatial assessment to psychometric tests leaving little room for a well-defined spatial curriculum. Although there are clear relationships between mathematics and spatial thinking, the independence in the measurement of the two constructs in research literature is rarely explored. In the present study, professionals in the fields of STEM Education and Cognitive Psychology evaluated mathematics and spatial assessment items. The results show evidence for a distinction between the two constructs in the content of the items, however with a caveat that thoughtful selection of assessment items is crucial to ensure independence in the measures.