Matching Pairs Concrete Operational StageOnline version This crossword puzzle is over key terminology related to Piaget's concrete operational stage. by Jennifer Paris 1 classification 2 seriation 3 conservation 4 reversibility 5 identity 6 decentration understanding that objects have qualities that do not change even if the object is altered in some way. understanding that changes in one quality can be compensated for by changes in another quality 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 arranging items along a quantitative dimension in a methodical way