Piaget's stages: Conservation and reversibility are mastered in which stage?

• A. Concrete operational
• B. Sensorimotor
• C. Pre-operational
• D. Formal operational

Answer: (A)

The main idea here is how children begin to think logically about real, concrete situations. In Piaget’s framework, the concrete operational stage is when kids start performing mental operations on tangible objects. They understand conservation—the amount of water remains the same even if the container’s shape changes—and they also grasp reversibility, meaning they can mentally undo a transformation, like pouring water back to its original container to restore the initial amount. This shift lets them reason about multiple aspects at once, not just what they see at the moment, and to solve problems by manipulating concrete objects in their minds.

Earlier than this, in the sensorimotor stage, thinking is linked to concrete actions and sensory experiences, with little to no understanding of conservation or reversibility. In the pre-operational stage, children may be able to use symbols but still struggle with conserving quantities and reversing operations. In the formal operational stage, reasoning becomes abstract and hypothetical, building on skills that were established earlier with concrete objects.