Oscar, a college student, is checking seven-year-old Gracie to see what cognitive skills she has. He asks her to do some basic conservation tasks. Gracie has correctly responded that there is still the same amount of clay, whether it is in a round ball or rolled out into a tube shape. When Oscar asks why, Gracie demonstrates how the tube-shaped piece of clay can be rolled back into a ball. This shows that she has a good grasp of