HookOne hillside in Rio holds the whole exam
Stand at the bottom of the Rocinha favela in Rio de Janeiro and you can see the entire section in one glance. Above you, tens of thousands of homes are stacked up a granite hillside — brick boxes, tangled electricity cables, alleys too narrow for a car — in the largest favela in Brazil. Below you, a few hundred metres away, sit the beachfront apartment blocks of São Conrado, where the same city sells flats for millions. One valley, two worlds. Rocinha exists because for sixty years people have poured out of the Brazilian countryside faster than any city could house them, and the gap between the two hillsides is what geographers mean by an urban challenge.
This is the story of the whole topic. In 2007 humanity crossed a line it had never crossed before: for the first time, more than half the world's population lived in towns and cities rather than in the countryside, and the UN projects that share will reach roughly 68% by 2050. Almost all of that growth is happening not in London or New York but in the cities of lower-income and newly emerging economies — Lagos, Mumbai, Rio — where a city can double in a generation. Every question in this section is a version of the same one: when a city grows that fast, who gets the opportunities, who gets the challenges, and how can the city be managed so it works for both?
ModelUrbanisation — the two engines of city growth
Urbanisation is the increase in the proportion of a population living in urban areas. That word 'proportion' matters: a country urbanises when the share of people in towns and cities rises, not simply when cities get bigger. A country can add city-dwellers and still see its urbanisation rate stall if the rural population grows just as fast.
Two engines drive it. The first is rural–urban migration — people moving from the countryside into cities. Geographers explain this with push and pull factors: people are pushed off the land by drought, poor harvests, mechanisation of farming, poverty and lack of services, and pulled towards cities by the promise of jobs, higher wages, schools, hospitals and electricity. The second engine is natural increase: migrants tend to be young adults of working and child-bearing age, so once they arrive the birth rate in the city stays high while death rates fall, and the population grows from within.
The pace differs sharply by wealth. High-income countries like the UK urbanised slowly during the Industrial Revolution and are now around 84% urban — the process is largely finished. Lower-income countries (LICs) and newly emerging economies (NEEs) are urbanising now, and fast, which is why the world's megacities — settlements of more than 10 million people — are increasingly found in Asia, Africa and South America. There are now more than 30 of them, and Tokyo, Delhi, Shanghai and São Paulo top the list.
DataReading urban growth — put a number on it
Examiners give you data on urban growth and expect you to work with it, not just describe the shape of the line. The single most useful calculation is percentage change, because it turns two population figures into one comparable statistic. The formula is: percentage change = (new value − original value) ÷ original value × 100.
When you interpret the answer, always link it back to the two engines from the previous block — a huge percentage rise is caused by rural–urban migration and natural increase working together, not one alone. The worked example below shows the move examiners reward: calculate, then explain.
Lagos, Nigeria's largest city, had a population of about 1.4 million in 1970. By 2020 it had grown to roughly 14 million. Percentage change = (14 − 1.4) ÷ 1.4 × 100 = 12.6 ÷ 1.4 × 100 = 900%. In fifty years the city grew by 900% — it became ten times larger. A full-mark answer does not stop at the number: it explains that such rapid growth is driven by rural–urban migration (people pushed off farmland by poverty and pulled to Lagos by industry and services) reinforced by natural increase, because the migrants are young and have children in the city. That single calculation plus one sentence of explanation is worth more marks than a paragraph of vague description.
CaseRio de Janeiro — opportunities and challenges in an NEE city
Rio de Janeiro sits in Brazil, a newly emerging economy, and its metropolitan area holds around 12 million people. Its growth has created real opportunities. Economically, the city is a hub for oil, finance, tourism and Brazil's media industry, and even the vast informal economy — street traders, unregistered workshops — gives arrivals a foothold and income. Socially, migration brings services within reach: healthcare and schooling in Rio are far better than in the rural interior, and the city offers electricity, clean water and entertainment that the countryside cannot.
But rapid growth has outrun the city's ability to house people, producing Rio's defining challenge: the favelas, or squatter settlements, home to around a fifth of the city's residents. Rocinha alone houses tens of thousands. Here the challenges stack up — many homes were self-built on steep, unstable slopes at risk of landslides; providing clean water, sanitation and a reliable electricity supply to unplanned settlements is extremely hard; formal jobs are scarce so unemployment and underemployment are high; and crime, especially linked to the drugs trade, has historically been severe. Traffic congestion chokes the wider city, and managing waste and air pollution is a constant struggle.
Rio's response is the part examiners want you to name. Rather than bulldozing favelas, the city has invested in upgrading them. The Favela Bairro Project paved roads, added drainage, lighting and health services, and legalised land ownership so residents would invest in their own homes. A cable car was built to connect the hillside Complexo do Alemão to the rest of the city. These are site-and-service and self-help schemes: the city provides the infrastructure and residents provide the labour — cheaper than clearance and far less destructive to the community.
CaseLondon — urban change in a UK city
AQA requires a case study of a major UK city as well, and London is the clearest. With around 8.9 million people, London shows how urban change creates social, economic and environmental opportunities and challenges. The opportunities are considerable: a cultural mix drawn from migration that makes the city one of the most diverse on Earth; world-class recreation and entertainment; huge employment in finance, tech, media and services; and an integrated transport system — Underground, buses, Overground and, since 2022, the Elizabeth line — that moves millions daily.
The challenges are just as real. London contains extremes of inequality: boroughs such as Newham and Tower Hamlets sit among the most deprived in England, a short distance from some of the wealthiest neighbourhoods in the country, with sharp differences in income, health and life expectancy. Housing is scarce and expensive, pushing the city outward into urban sprawl and putting pressure on the surrounding Green Belt. Building on greenfield land is cheaper but destroys countryside, while reusing brownfield (previously developed) land is more sustainable but costs more to clear. Add dereliction in older industrial areas, waste disposal for millions of people, and air pollution, and you have the full set.
London's headline answer is urban regeneration. The clearest example is the Lower Lea Valley in east London, a derelict, contaminated industrial zone transformed for the 2012 Olympics into the Queen Elizabeth Olympic Park. Regeneration reused brownfield land, cleaned polluted ground, built thousands of new homes and a new transport interchange at Stratford, and brought jobs to one of the city's poorest districts. The examiner's follow-up is always the same: regeneration creates opportunity, but does it price out the original residents? Holding both sides is the mark of a strong answer.
MechanismSustainable urban living — making the growth last
The final idea is urban sustainability: meeting the needs of people in cities today without wrecking the environment for future generations. AQA breaks it into resource management and transport, and both come with named examples.
On resources, sustainable cities conserve water (metering, recycling grey water, harvesting rainwater), conserve energy (insulation, solar panels, combined heat and power), create and protect green space for wellbeing and drainage, and cut waste through recycling. The model example is the Vauban district of Freiburg, Germany: a neighbourhood of roughly 5,000 people built to be car-reduced, with houses so well insulated and solar-equipped that many generate more energy than they use. In the UK, the BedZED development in Sutton, south London, does the same on a smaller scale.
On transport, the challenge is congestion — which wastes time, pumps out air pollution and damages the economy. Solutions centre on integrated transport systems that let people switch smoothly between modes, and on discouraging car use. London introduced a congestion charge in 2003, charging drivers to enter the centre (now £15 a day), which cut traffic and funded public transport. The city of Curitiba in Brazil built a famous bus rapid transit system decades ago, moving huge numbers cheaply. The principle that ties the section together: a sustainable city manages its growth so that opportunity does not have to come at the environment's expense.
VocabularyKey terms the mark scheme pays for
TrapsMisconceptions that cost marks
ExamWhat examiners want
Paper 2 marks against four assessment objectives, and urban questions lean on AO2 (understanding interrelationships) and AO3 (applying knowledge to analyse and evaluate). The high-tariff questions are 6 and 9 marks, marked in levels — Level 1 is basic (1–3), Level 2 is clear (4–6), Level 3 is detailed and well-developed (7–9). One 9-marker per paper also carries 3 marks for spelling, punctuation and grammar, so write in full, accurate sentences.
The non-negotiable for this section is named, specific case studies. AQA requires one LIC/NEE city (use Rio de Janeiro) and one UK city (use London), and generic answers about 'a city in a poor country' are capped at the bottom level. Drop in the specifics — Rocinha, the Favela Bairro Project, the Lower Lea Valley, the 2012 Olympic Park, the London congestion charge — because places and figures are exactly what the AO1 marks reward.
Watch the command word. 'Assess', 'Evaluate' and 'To what extent' demand a two-sided argument ending in a clear judgement — state which side is stronger and why, rather than listing points. When a figure, graph or photograph is provided, use it: quote a value, describe a trend, or calculate a percentage change (AO4 skills marks are handed out for exactly this). And keep opportunities and challenges balanced — the strongest evaluations show that the same urban change, such as regeneration, can be an opportunity for one group and a challenge for another.