One-year-old Danny is fascinated with flushing the toilet and throwing different objects down the bowl. Flushing to see the water go down shows . The fact that Danny is expecting to see things reappear again after they are out of sight shows he understands the basics of object permanence.

Urban growth invariably feeds increased commercialization and industrialization. it requires continually expanding land areas. when urbanization rates are high, and countries do not have the institutional and managerial capacities or economic wherewithal to manage such rapid growths, they exert intense pressure on the types and nature of the resulting settlements. they contribute to the development of overcrowded slums and shanty towns without adequate essential services and necessary infrastructure.-by asit k. biswas and cecilia tortajada