Piaget's stages criteria

• Conservation


  The ability to realise that quantity remains the same even when the appearance changes
• Egocentric


  Can only see the world from their point of veiw
• Object permanence


  The ability to know that an object still exists even if it is not visible
• Sensory and motor contact


  The ability to controll movements and grab things using hands
• Separation anxiety


  Feeling distressed when separated from a person or thing, usually a parent or carer
• Language


  The ability to talk or communicate
• Formal reasoning 


  Being capable of reasoning
• Concrete


  Physical objects