Robert's mother pours a cup of milk for him and then realizes that the cup has a small crack in the rim. Not wanting her son to cut his lip, she pours the milk into another cup. The second cup happens to be shorter and wider than the first cup. Robert is not upset because he knows that the amount of milk has remained the same. Robert is at LEAST _____ years old.
A) 3
B) 5
C) 7
D) 9

Question

Quizplus · Accepted Answer

Robert's understanding that the amount of milk has remained the same indicates that he has a grasp on conservation, which is a cognitive milestone typically achieved around the age of seven.

Robert's Mother Pours a Cup of Milk for Him and Then