Three-year-old Devesh gets upset because he believes his sister's glass has more juice than his glass does. Both of them have the same amounts of juice but Devesh is confused because of the difference in the shape of their juice glasses. According to Piaget, this would be an example of Devesh's

Lack of conservation.

Explanation:

Lack of Conservation defined is 'Realizing that something can have the same properties even if it appears differently'.

Lack of conservation

Explanation:

Jean Piaget divided children's cognitive development in different stages.

According to him, children between the ages of two and seven years are in the preoperational stage.

One important characteristic of this stage is the Lack of Conservation. He demonstrated this idea with a classic experiment. He placed two glasses in front of children who were this age. Then he proceed to pour the water that was in a glass into a taller but thinner glass. He then proceed to ask the children which of the two glasses contained more water, children in this stage answered that the taller glass contained more water. This proves that children just focused on one of the dimensions and couldn't separate shape from quantity.

Therefore, this characteristic refers to the inability of children to preserve preserve something in the face of physical change.

In the example both glasses have the same quantity of juice but the shape of them confuses Devesh so this is an example of lack of conservation.