Which concept explains that a given quantity remains the same despite changes in shape or container?

• A. Puberty
• B. Conservation
• C. Identity vs. role confusion stage
• D. Egocentric

Answer: (B)

Conservation is the understanding that a quantity stays the same even when its appearance changes, such as pouring water from a tall, thin glass into a short, wide dish. This invariance under perceptual transformations is a key part of developing logical thinking about quantity. It signals that a child has moved into the stage where they can reason about reversible processes and understand that volume, number, or mass remains constant despite changes in shape or arrangement. For example, the amount of water doesn't increase or decrease just because the container looks different, and the same idea applies to objects like a line of coins or a lump of clay that can be reshaped without changing the total amount.

The other options don’t fit because they describe unrelated concepts: puberty refers to biological changes during adolescence, identity vs. role confusion is Erikson’s psychosocial stage about self and social roles, and egocentric describes a preoperational tendency to view the world only from one’s own perspective.