In Piaget's theory, the concept that a substance's weight, mass, and volume remain the same even if its shape changes is called what?

• A. Reversibility
• B. Identity
• C. Seriation
• D. Conservation

Answer: (D)

Conservation is the idea that a quantity remains the same even when its appearance changes. In Piaget's terms, mass, weight, and volume stay constant when you reshape or rearrange matter. For example, rolling clay into a ball or flattening it doesn’t change how much clay there is, and pouring water into a differently shaped container doesn’t create more or less water. This shows invariance under transformation, a concept children typically grasp once they reach the concrete operational stage when they can reason about more than just what’s immediately visible. Reversibility is about mentally undoing actions, seriation is about ordering by a dimension, and identity concerns recognizing something as the same despite changes in appearance; conservation specifically captures the preservation of quantity across transformations.