AUTHOR=El-Hamamsy Laila , Zapata-Cáceres María , Marcelino Pedro , Bruno Barbara , Dehler Zufferey Jessica , Martín-Barroso Estefanía , Román-González Marcos TITLE=Comparing the psychometric properties of two primary school Computational Thinking (CT) assessments for grades 3 and 4: The Beginners' CT test (BCTt) and the competent CT test (cCTt) JOURNAL=Frontiers in Psychology VOLUME=Volume 13 - 2022 YEAR=2022 URL=https://www.frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2022.1082659 DOI=10.3389/fpsyg.2022.1082659 ISSN=1664-1078 ABSTRACT=With the increasing amount of research around Computational Thinking (CT) and endeavours introducing CT into curricula worldwide, assessing CT at all levels of formal education is of utmost importance to ensure CT-related learning objectives are met. This has contributed to a progressive increase in the number of validated and reliable CT assessments for K-12, including primary school. Researchers and practitioners are thus required to choose among multiple instruments, often overlapping in their age validity. In this study we compare the psychometric properties of two of these instruments: the Beginners' CT test (BCTt), developed for grades 1-6, and the competent CT test (cCTt), validated for grades 3-4. Classical Test Theory and Item Response Theory were employed on data acquired from 575 students in grades 3-4 to compare the properties of the two instruments and refine the limits of their validity. The findings establish the detailed psychometric properties of the BCTt in grades 3-4 for the first time, and through a comparison with students from the same country, indicate that the cCTt should be preferred for grades 3-4 as it is able to discriminate between students of low and medium ability. Conversely, while the BCTt, which is easier, shows a ceiling effect, it is better suited to discriminate between students in the low ability range. For these grades, the BCTt can thus be employed as a screening mechanism to identify low ability students. Finally, the findings highlight the importance of comparing the psychometric properties of existing assessments, so that researchers and practitioners, including teachers and policy makers involved in digital education curricular reforms, may take informed decisions when selecting assessments.