The Case of Felicia: A Young Child’s Strategies for Reducing Memory Demands During Mental Addition

A semi-structured clinical interview technique was used in an intensive case study of a preschool child’s addition ability. The interviews uncovered a novel mental addition strategy: counting-all starting with the larger addend. This strategy minimizes the cognitively demanding double count required by mental addition strategies. Moreover, another invented strategy, a counting-on- like variation, was employed with problems involving a double-digit addend to reduce mental effort.