It is suggested that the classical conservation justifications (reversibility, compensation, identity, identity action) are both formally and empirically inadequate justifications for the conservation deduction, particularly from a pedagogical perspective. A test for the distinction between true and empirical reversibility, that subjects know of…

A conservation problem of numerical equivalence which 80% of adults reliably fail and 40% of third graders pass was developed, and responses of 188 subjects (Grades 2, 3, 5, 7, 9, 11 and college) to it and related number conservation and probability problems indicated that the differences in nonconservation were rooted in subjects' different…