Suddenly, around the age of 5 to 7, the average child catches on to the conservation experiments. This marks the transition to a new stage of development: the concrete operational period. Now the child can understand simple operations performed on concrete reality: operations like pouring a beaker of water from one vessel to another.
Why does the child suddenly pass the same tests he or she failed a year earlier? Piaget felt the child had jumped up to a new stage of development. The child now has a mental representation or schema for liquid quantity, mass, number, and other such concepts. Some conservation problems are easier than others, but within a year or two they are all mastered. In fact, the child now finds these problems so easy that he or she is likely to wonder why an adult is asking such silly http://spokane-webdesigns.net/ questions. “Of course the two beakers have the same amount of liquid in them…”
Piaget and his co-workers did not call a child a conserver until the child could explain the conservation experiment. This guarded against children learning to say, “Yes, they are equal” in conservation experiments, without really understanding what was going on.