For example, two drinking glasses, one being short and broad while the other tall and thin, are presented to 3-year-olds and 9-year-olds. Some liquid is poured into the short class until half-filed, and then it is poured into the tall glass that fills it to the brim. When 3-year-olds are asked which glass has more liquid, they will respond that there is more in the tall one (Siegler, Ellis, 1996). Yet, when one asks children where that extra quantity came from, they do not know (Marlowe, Canestrari, 2006). 9-year-olds, however, are more likely to say that there is an equal amount of liquid in both because they understand that when liquid is poured from one glass into another it does not disappear (Feldmanm, 2014). The knowledge of the relationship between the quantity and physical appearance of objects is achieved during concrete operational stage, and is called conservation. Another concept that children in preoperational stage lack, but those that have reached concrete operational understand is transformation. It is defined by Feldmanm as an action during which one state is changed into another. For example, when a pencil is held upright and then allowed to fall, 9-year-olds will know that it goes through multiple stages before it reaches the ground. 3-year-olds, on the other hand, lack that concept. Therefore, they do not see the intermediate positions and only recognize the initial and the final locations of the pencil (Feldmanm,
For example, two drinking glasses, one being short and broad while the other tall and thin, are presented to 3-year-olds and 9-year-olds. Some liquid is poured into the short class until half-filed, and then it is poured into the tall glass that fills it to the brim. When 3-year-olds are asked which glass has more liquid, they will respond that there is more in the tall one (Siegler, Ellis, 1996). Yet, when one asks children where that extra quantity came from, they do not know (Marlowe, Canestrari, 2006). 9-year-olds, however, are more likely to say that there is an equal amount of liquid in both because they understand that when liquid is poured from one glass into another it does not disappear (Feldmanm, 2014). The knowledge of the relationship between the quantity and physical appearance of objects is achieved during concrete operational stage, and is called conservation. Another concept that children in preoperational stage lack, but those that have reached concrete operational understand is transformation. It is defined by Feldmanm as an action during which one state is changed into another. For example, when a pencil is held upright and then allowed to fall, 9-year-olds will know that it goes through multiple stages before it reaches the ground. 3-year-olds, on the other hand, lack that concept. Therefore, they do not see the intermediate positions and only recognize the initial and the final locations of the pencil (Feldmanm,