In an experiment, two-year-old boys and their fathers made pie dough together using rolling pins and other utensils  Each father-son pair used a rolling pin that was distinctively different from those used by the other father-son pairs, and each father repeated the phrase rolling pineach time his son used it
But when the children were asked to identify all of the rolling pins among a group of kitchen utensils that included several rolling pins, each child picked only the one that he had used
The children did not grasp the function of a rolling pin.