ABSTRACT
Instruction in fractions is often a critical turning point in mathematics learning. Many children who have had no trouble learning the basics of counting and whole-number arithmetic meet with serious difficulty when it comes to lessons on fractions. The notion that innate structures like the accumulator might support natural number concepts but not fractions is a somewhat startling one from an evolutionary perspective, however. The guiding assumption in domain-specific theories is that cognitive structures like the accumulator have evolved because they contribute to survival and reproduction. Knowledge of fractions develops over an extraordinarily long period of time. Despite the difficulties which even sixth-graders like Anita continue to have in reasoning about fractions, children already have some fraction-related knowledge as early as the preschool period. Unit fractions are formed by partitioning the whole into equal parts; these parts then serve as a unit of measurement in constructing non-unit fractions.
