There are many processes that support scientific reasoning. For example, one recent finding is that when children are prompted to engage in predicting an event’s outcome, learning is boosted as compared to learners who are prompted to evaluate it post hoc. One possible explanation for this “prediction boost” is that it helps learners engage metacognitive reasoning skills that may not be spontaneously leveraged, especially for individuals with still-developing executive functions. In this paper, we combine multiple analytic approaches to investigate the potential role of executive functions in elementary school-aged children’s science learning. We present an experiment that investigates children’s science learning during a water displacement task where a “prediction boost” had previously been observed – children either made an explicit prediction or evaluated an event post hoc (i.e., postdiction). In this paper we consider the relation of executive function measures and learning, which were collected following the main experiment. Via mixed effects regression models, we find that stronger executive function skills, (i.e., stronger inhibition and switching scores), were associated with higher accuracy in Postdiction but not in the Prediction Condition. Using a theory-based Bayesian model, we fit children’s individual performance on the learning task (capturing “belief flexibility”), comparing this “flexibility” to the other measures to understand the relationship between belief revision, executive function, and prediction. Children in the Prediction Condition showed near ceiling “belief flexibility” scores, and significantly higher than children in the Postdiction Condition. We also found a significant correlation between children’s executive function measures (as given by inhibition and switching in the posttest) to our “belief flexibility” parameter, but only for children in the Postdiction Condition. These results indicate that when children are providing responses post hoc, they may require stronger metacognitive capacities to navigate the learning task. Additionally they suggest that, especially for individuals who might otherwise struggle due to still-developing executive functions, the prediction boost is explained by increased flexibility in the belief revision process.