We argue that understanding the cognitive foundations of computational thinking will assist educators to improve children's learning in computing. We explain the conceptual relationship between executive functions and aspects of computational thinking. We present initial empirical data from 23 eleven year old learners which investigates the correlation between assessments of programming and debugging in the visual language Scratch and scores from the BRIEF2 assessment of executive functions. The initial data shows moderate to large correlations between assessments of debugging and programming with the BRIEF2 teachers' rating of executive function as manifested in classroom behaviour. Case studies from the empirical data are used to qualitatively illustrate how executive functions relate to a game making task. We discuss the implications of these findings for educators, and present suggestions for future work.