The preschool period is a time of rapid growth along a number of developmental measures, not the least of which is children’s thinking abilities, or cognition. Across this time period, children learn to use symbolic thought, the hallmarks of which are language and symbol use, along with more advanced pretend play. Children this age show centration of thought, meaning their focus is limited to one aspect of a situation or object. Memory abilities come online and children show their own ways of categorizing, reasoning, and problem solving.