The puzzling difficulty of tool innovation: why can't children piece their knowledge together?

Tool innovation-designing and making novel tools to solve tasks-is extremely difficult for young children. To discover why this might be, we highlighted different aspects of tool making to children aged 4 to 6 years (N=110). Older children successfully innovated the means to make a hook after seeing the pre-made target tool only if they had a chance to manipulate the materials during a warm-up. Older children who had not manipulated the materials and all younger children performed at floor. We conclude that children's difficulty is likely to be due to the ill-structured nature of tool innovation problems, in which components of a solution must be retrieved and coordinated. Older children struggled to bring to mind components of the solution but could coordinate them, whereas younger children could not coordinate components even when explicitly provided.