Urban and rural areas, population density, why cities grow and what they are known for, urban problems such as housing and air quality, and city planning.
Key ideas
Urban areas are dense, with varied jobs and municipal bodies; rural areas are villages with mostly farm jobs and gram panchayats.
Each country sets its own size for “urban”: about 5,000 people in India.
Urbanisation is the shift of people from villages to towns and cities.
Cities grow from a good location such as a port, industry and jobs, trade, finance and government offices.
Slums form where there is not enough affordable housing for people who come for work.
Built-up areas trap heat (heat islands), and lost lakes, as in Bengaluru, cause floods and water shortages.
Urban planners decide how land is used, guided by a city’s Master Plan; vertical gardens add green where land is scarce.
Thinking “urban” means the same size everywhere: each country sets its own.
Finding density as area ÷ people: it is people ÷ area.
Thinking a higher AQI is better: higher means more polluted air.
Worked example
A city’s AQI fell from 350 to 150 after it planted trees and cut traffic. By how much did it fall, and how many times the safe level of 50 is the new reading?