According to piaget’s theory of cognitive development we actively construct our cognitive world using

We actively construct knowledge about the world by exploring and interacting with it. That means that we can know the theory about something but until we try it we won't know how to do it. That's how children work. You can tell them how block building works but until they start building blocks themselves they won't know how to do it. Same when you're an adult. You can read a book about car fixing, but you won't know how to do it until you open the car and start working on it.

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