Depends on what you mean by children. Most of these concepts appear as a child ages but I think they get out of the simple ones pretty early. I know before a c

Depends on what you mean by children. Most of these concepts appear as a child ages but I think they get out of the simple ones pretty early. I know before a certain developmental state children will say a taller thin glass holds more then a short wide glass even if you pour them back and forth to show they are equivalent. Once they "get" the concept it is for life but before that it is impossible, logic be dammed.