This study explored prefrontal cortex (PFC) activation in elementary students during biomimicry-based convergent thinking using functional near-infrared spectroscopy (fNIRS). Sixteen sixth-grade students completed a task consisting of Exploration, Design, and Implementation phases while their hemodynamic responses were recorded. Each phase showed distinct neural activation patterns. The Exploration phase elicited significant activation in the left dorsolateral prefrontal cortex, reflecting intensive verbal working memory and information manipulation. During the Design phase, broader PFC activation was observed in the right dorsolateral and ventrolateral prefrontal cortices and the left frontal pole, indicating imagery-based creative synthesis, planning, and goal-directed multitasking. The Implementation phase mainly involved the right ventrolateral prefrontal cortex and left frontal pole, suggesting increased demands on cognitive flexibility, self-regulation, and error monitoring. Previous neurodevelopmental studies have reported that adolescents tend to demonstrate greater neural efficiency and more distributed network engagement during complex cognitive tasks. In contrast, the present findings suggest that elementary students rely more heavily on core PFC resources to manage cognitive load during biomimicry-based convergent thinking. These findings highlight the need for convergent education at this level to emphasize instructional scaffolding that reduces cognitive overload and supports the development of executive functions, particularly planning and monitoring.