Matching Pairs Concrete Operational StageOnline version This crossword puzzle is over key terminology related to Piaget's concrete operational stage. by Jennifer Paris 1 identity 2 reversibility 3 conservation 4 seriation 5 decentration 6 classification understanding that objects have qualities that do not change even if the object is altered in some way. arranging items along a quantitative dimension in a methodical way understanding that things that have been changed can be returned to their original state organizing objects by a variety of characteristics (size, color, shape, etc.) considering changes in more than one dimension understanding that changes in one quality can be compensated for by changes in another quality