The development of children's self-concept evolves by means of

This happens through regular self-evaluation when faced with many different problems and situations.
The image of self and really the knowledge of our self concepts is of paramount importance. Children first develop this self concept at the early age and they define themselves through things like their age, gender, family members and possessions.Throughout their development they will evolve this self-concept through self-evaluation and introspection to the situations they encounter.  

Old telephone. is prehistoric object