The Card Sorting Task is an iPad-based assessment of 'shifting' (an executive function that involves the ability to control and redirect attention). In this game, children are presented with cards that vary along two dimensions (i.e., shape and colour) and are asked to sort each card (i.e., red rabbits and blue boats) first by one dimension (e.g., colour) and then, after a number of trials, by another dimension (e.g., shape). Their ability to flexibly shift from one sorting rule to another corresponds to their cognitive flexibility (or 'shifting'). This game takes approximately 5 minutes to complete.The 'Early Years Toolbox' (EYT, for short) is comprised of six brief, engaging game-like assessments of young childrens self-regulation, executive functioning and vocabulary. These games are based on well-established and widely used measures for young children (e.g., go/no-go, dimensional change card sort), yet have been adapted and optimised on the basis of 20+ years of research experience with this age group.NOTE FOR RESEARCHERS. If using this app for research and/or publication purposes, please cite the following as the original source articles (please feel free to contact us for copies of these articles):Howard, S. J., & Okely, T. (2015). Catching fish and avoiding sharks: Investigating factors that influence developmentally appropriate measurement of preschoolers inhibitory control. Journal of Psychoeducational Assessment, 33(6), 585-596.Howard, S. J., & Melhuish, E. (2015). An Early Years Toolbox (EYT) for assessing early executive function, language, self-regulation, and social development: Validity, reliability and preliminary norms. Manuscript submitted for publication.