How old is Phillip likely if he knows to give his sister the taller glass although both glasses hold the same amount?

Phillip's ability to understand that the taller glass appears to hold more liquid, even though both glasses contain the same amount, indicates a level of cognitive development that aligns with the concrete operational stage, as described by Piaget. Typically, children reach this stage between the ages of 7 and 11 years. By eight years old, children are more capable of understanding concepts of volume and can manipulate ideas mentally rather than relying solely on visual appearance.

At this age, they can recognize that appearances can be deceiving and that two objects can be equal in volume despite differences in height or shape. This cognitive ability reflects an important developmental milestone where logical thinking and operational thought become more pronounced. Therefore, Phillip's awareness of the equivalency of the liquid in differently shaped glasses suggests he is likely eight years old, which aligns well with the cognitive abilities expected at that age.