The impact of spatial ability on STEM achievement has gained significant attention from researchers, yet progress remains limited by inadequacies in available spatial assessment tools. Current spatial tests present numerous challenges: limited accessibility, questionable psychometric properties, theoretical inconsistencies, and gaps in STEM-relevant skill measurement. In fact, there is a lack of consensus about what a taxonomy of spatial skills would look like and how those skills should be assessed. This project will advance the field by addressing these critical limitations through a transformative methodological approach. Researchers will conduct comprehensive scoping reviews to examine current test usage and develop recommendations for improvement. They will then develop and make publicly available a series of open-source spatial tests, featuring refined existing assessments and new tools developed through collaboration with cognitive science and education research communities. The research team will determine the underlying psychometric structure of spatial abilities and their relationship to STEM learning by implementing rigorous evaluations of multiple spatial tests and using such approaches as Rasch modeling and exploratory factor analysis. They will develop new assessments, building upon scoping review findings, ensuring high visual quality and open-source compatibility. The project will implement Open Science Standards for data sharing, enabling researchers to a