A mom in Ila’s preschool class shared this test with us:
Show the child two glasses of the same size, filled equally with water. Ask him if they contain the same amount. When he confirms this, take one of the glasses and pour all of the water into a taller, thinner glass. Then, ask him, “Do these two glasses contain the same amount of water, or does one have more?” A child who says that the taller glass contains more water has not yet obtained understanding of concrete operations. A child has obtained concrete operations, Piaget’s third stage of development, when he begins understanding concrete measures of conservations such as liquid, number, length, mass and weight.