Answer by  
                                                                                          bettylou (69)
                                                            
                          
                          
                                                          The first stage is The Sensorimotor Period which is approximately birth - two years.  The childs cognitive system is limited to motor reflexes at birth which develops to more complicated relexes.
 Second, PreOperational Thought two - six or seven years. 
 Third, Concrete Operations six/seven - eleven/twelve years.
 Fourth, Formal Operations eleven/twelve - adult.