In one of the tasks devised by Piaget, a child is shown two…

In one of the tasks devised by Piaget, a child is shown two identical beakers filled to the same level with liquid. Next, the liquid from one beaker is poured into a third beaker, which is taller and thinner than the first two. Then, the child is asked if the amount of liquid in the tall, thin beaker is equal to that which remains in one of the original beakers. The child’s awareness of which of the followings concepts is tested by this task?