We investigated the role of children's conflict monitoring skills in revising an intuitive scientific theory. Children aged 5 to 9 (N = 177; 53% girls, data collected in Germany from 2019-2023) completed computer-based tasks on water displacement, a concept prone to misconceptions. Children predicted which of two objects would displace more water before receiving feedback. With increasing age, children showed slower response times for incorrect predictions ([beta] = -0.04) and greater pupil dilation to unexpected outcomes ([beta] = -0.04), indicating better conflict monitoring. Better conflict monitoring, in turn, predicted faster belief revision ([beta] = 0.07). These findings suggest that conflict monitoring is crucial for learning in discovery-based activities.