When does conservation of volume typically become understood?

• A. Around age 7–8 years (concrete operational stage).
• B. Around age 4–5 years (preoperational stage).
• C. Around age 10–11 years (formal operational stage).
• D. In infancy.

Answer: (A)

Conservation of volume shows concrete operational thinking at work—the child can use reversible thinking and decenter from appearances to understand that the amount of liquid stays the same even when its container changes shape. This typically emerges around seven to eight years old. Before then, in the preoperational period, children focus on how things look and have trouble with reversibility, so they might believe the taller container has more liquid. By infancy there’s no grasp of this concept, and by the formal operational stage (early adolescence) they can think more abstractly, but the conservation idea is already established by this age range.