World population has grown from 1 billion in 1804 to over 8 billion. Understanding why helps planners prepare for the future.
🔢 Births, deaths and growth
Birth rate and death rate are the number of births and deaths per 1000 people per year. Natural increase = birth rate − death rate (per 1000), so a rate of 10 per 1000 is 1% growth. The fertility rate is births per woman; about 2.1 keeps a population stable. The demographic transition model has 4 or 5 stages: high birth and death rates (stage 1), falling death rate (stage 2), falling birth rate (stage 3), low and balanced rates (stage 4).
birth rate 30, death rate 10 → natural increase 20 per 1000 = 2%
fertility 2.1 → replacement level
fertility 1.3 (e.g. South Korea) → shrinking population
🖼️ See it
A wide base means many children: a young, fast-growing population (typical of low-income countries).A narrow base and a bulge at the top: few births and many older people (typical of Japan or Italy).
👵 Age structures
A population pyramid shows age and sex. A wide base means many children (high birth rate, as in Niger); a narrow base and wide top means an ageing population (as in Japan). The dependency ratio compares people under 15 and over 64 with those of working age. An ageing population raises costs of pensions and healthcare, while a youthful one needs schools and jobs. Population policies include China’s one-child policy (1980–2015).
dependency ratio = (young + old) / working age × 100
(20 + 10) / 70 × 100 = 42.9 per 100
The shape of the pyramid tells a story. Look at the base for births and the top for life expectancy.
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Natural increase
Natural increase is:
Subtract.
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Replacement
A fertility rate of about 2.1 means the population is:
Level.
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Pyramid
A wide base on a population pyramid shows:
Look at the base.
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Ageing
An ageing population causes:
Costs.
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A country has a birth rate of 30 and a death rate of 10 per 1000.
What is the natural increase per 1000?
Enter an exact answer, without rounding.
per 1000
Subtract.
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Natural increase is 20 per 1000.
What is this as a percentage growth rate?
Enter an exact answer, without rounding.
%
Divide by 10.
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A population of 50 million grows by 2% a year.
How many extra people after one year, in millions?
Enter an exact answer, without rounding.
million
2% of 50.
📝 Lesson quiz · 5 questions
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Re-read the lesson, then give it another go.
Question 1 of 5
The demographic transition model describes:
Question 2 of 5
Which stage has falling death rates but high birth rates?
Question 3 of 5
Japan’s pyramid has:
Question 4 of 5
A dependency ratio compares:
Question 5 of 5
China’s one-child policy ended in:
Lesson 2 · Human geography
🧳 Migration
People move for many reasons. Migration changes both the places they leave and the places they arrive.
➡️ Types and causes
Migration is a change in usual residence. Internal migration is within a country; international migration crosses borders. Voluntary migrants move for work or family; forced migrants flee conflict or disaster. A refugee is someone fleeing persecution who has crossed a border; an asylum seeker has applied for protection. Net migration = immigrants − emigrants. Over 280 million people live outside the country they were born in.
For destination countries: migrants fill labour shortages and boost the economy, but can strain housing and services and cause social tension. For origin countries: remittances (money sent home) are large — over $600 billion a year to low and middle-income countries — but there can be a brain drain of skilled workers. Policies include visas, quotas, integration programmes and refugee resettlement.
remittances: $600 billion a year
brain drain: doctors and engineers leave
EU free movement: citizens can live and work in any member state
Migration has costs and benefits on both sides. Avoid one-sided generalisations.
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Refugee
A refugee is someone who:
Forced.
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Remittance
Remittances are:
Sent back.
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Brain drain
Brain drain means:
Loss of skills.
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Internal migration
Moving from a village to a city in the same country is:
Same country.
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A country receives 100 000 immigrants and loses 60 000 emigrants in a year.
What is the net migration?
Enter an exact answer, without rounding.
Subtract.
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A worker sends home $200 each month.
How much in a year, in $?
Enter an exact answer, without rounding.
$
Multiply by 12.
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Of 280 million international migrants, about 15% are refugees or asylum seekers (round).
About how many million is that?
Round your answer as the question asks.
million
15% of 280.
📝 Lesson quiz · 5 questions
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Re-read the lesson, then give it another go.
Question 1 of 5
A push factor is:
Question 2 of 5
An asylum seeker is:
Question 3 of 5
One benefit migrants bring to a destination is:
Question 4 of 5
Which is a forced migration?
Question 5 of 5
Net migration is positive when:
Lesson 3 · Human geography
📊 Development
Countries differ in income, health and education. Indicators help us measure these differences and ask what causes them.
📏 Measuring development
Development is improvement in wellbeing. GDP per capita = total output ÷ population. The Human Development Index (HDI) combines income, life expectancy and education, scored 0 to 1. Others: infant mortality, adult literacy, access to clean water. Countries may be grouped as HICs (high-income), LICs (low-income) and NEEs (newly emerging economies, such as China, India, Brazil).
GDP per capita = GDP / population
$2 trillion / 50 million = $40 000
Norway HDI ≈ 0.96 (very high)
Niger HDI ≈ 0.39 (low)
🖼️ See it
No single number captures development, so geographers combine economic and social indicators such as the Human Development Index.
🧩 Causes and strategies
Causes of unequal development: colonial history, conflict, poor governance, debt, climate and trade rules. Strategies: aid (grants and loans), fair trade, debt relief, microfinance (small loans), and intermediate technology (appropriate, low-cost tools). Most countries of the world have improved life expectancy by about 10 years since 1990.
microfinance: a loan of $100 buys a sewing machine
aid: $100 billion a year from rich countries
HDI measures progress, not equality
GDP is not the whole story. A country can be rich on average and still unequal.
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HDI
The HDI combines:
Three parts.
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GDP per capita
GDP per capita is:
Per person.
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Microfinance
Microfinance provides:
Tiny loans.
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NEE
NEE stands for:
Rapid growth.
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A country’s GDP is $2 trillion ($2 000 000 million) and its population is 50 million.
What is the GDP per capita, in $?
Enter an exact answer, without rounding.
$
Divide by 50.
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Life expectancy in a country rose from 60 to 72 years.
By how many years did it rise?
Enter an exact answer, without rounding.
years
Subtract.
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Infant mortality fell from 80 to 20 deaths per 1000 births.
By what percentage did it fall?
Enter an exact answer, without rounding.
%
Fall ÷ original × 100.
📝 Lesson quiz · 5 questions
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Re-read the lesson, then give it another go.
Question 1 of 5
A reason for low development in some countries is:
Question 2 of 5
Which indicator measures health?
Question 3 of 5
Fair trade aims to:
Question 4 of 5
Intermediate technology is:
Question 5 of 5
Debt relief means:
Lesson 4 · Human geography
🏙️ Urbanisation
For the first time in history more than half of humanity lives in cities. The pace of growth brings opportunities and problems.
🌆 Why cities grow
Urbanisation is the growing share of people living in towns and cities. It is driven by rural–urban migration (push: poverty, mechanised farming; pull: jobs, services) and natural increase. HICs urbanised in the 1800s; in LICs and NEEs urbanisation is now fastest. Over 56% of people live in cities, rising to about 68% by 2050. Megacities (10 million+) include Tokyo, Delhi, Shanghai and São Paulo.
Figures are approximate (UN estimates). The dashed section is a projection.
🏚️ Challenges and solutions
Rapid growth creates informal settlements (slums, favelas) with poor sanitation, traffic congestion, air pollution and unemployment. About 1 billion people live in slums. Solutions: self-help schemes (improving homes with local labour), site-and-service plots, public transport such as bus rapid transit, and smart growth with compact, mixed-use neighbourhoods. In HICs, regeneration reuses derelict land.
Rio de Janeiro: favela improvement, cable cars, paved paths
Curtiba, Brazil: bus rapid transit
1 billion in slums out of about 4.5 billion urban people ≈ 22%
Cities concentrate both opportunity and risk. Planning decides which one grows.
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Urbanisation
Urbanisation is the:
More urban.
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Megacity
A megacity has at least:
Very large.
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Informal settlement
An informal settlement is:
Unplanned.
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Bus rapid transit
Bus rapid transit reduces:
Efficient transport.
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Urban population was 56% in 2020 and is projected at 68% in 2050.
By how many percentage points will it rise?
Enter an exact answer, without rounding.
points
Subtract.
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A city grows by 3% a year from 10 million.
How many people are added in one year, in thousands?
Enter an exact answer, without rounding.
thousand
3% of 10 million.
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A city of 8 million has 2 million people in slums.
What percentage live in slums?
Enter an exact answer, without rounding.
%
Divide, ×100.
📝 Lesson quiz · 5 questions
0 / 5
Re-read the lesson, then give it another go.
Question 1 of 5
Which is a push factor from rural areas?
Question 2 of 5
Self-help housing schemes:
Question 3 of 5
Which city is famous for bus rapid transit?
Question 4 of 5
A problem of rapid urbanisation is:
Question 5 of 5
Regeneration means:
Lesson 5 · Environment and society
🌏 Global Issues
Some challenges cross borders. Climate, food and water affect everyone, and solutions need cooperation.
🔥 Climate change basics
The greenhouse effect traps heat; extra carbon dioxide from fossil fuels strengthens it. Global temperature has risen about 1.1–1.2 °C since the late 1800s. Effects: melting ice, rising sea level, heatwaves, stronger storms and shifting rainfall. The Paris Agreement (2015) aims to keep warming well below 2 °C, ideally 1.5 °C. Mitigation cuts emissions; adaptation prepares for the changes.
CO₂ before industry: ~280 ppm
CO₂ today: ~420 ppm
increase: 420 − 280 = 140 ppm (50%)
Paris target: well below 2 °C
🖼️ See it
Each problem makes the others worse, so solving them needs cooperation between countries.
🌾 Food and water
About 735 million people go hungry; 2 billion lack safely managed drinking water. Food security means reliable access to enough nutritious food. Threats: drought, conflict, poverty and food waste (about one third of food produced is wasted). Solutions: drip irrigation, drought-tolerant crops, reducing waste and better storage.
food wasted: 1/3 of production
if production is 3 billion tonnes → 1 billion tonnes wasted
drip irrigation: saves up to 50% of water
Mitigate and adapt. We need to reduce emissions and prepare for the change already happening.
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Greenhouse
The main gas increasing the greenhouse effect is:
CO₂.
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Mitigation
Mitigation of climate change means:
Cut the source.
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Adaptation
Adaptation includes:
Cope with change.
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Food security
Food security means:
Enough to eat.
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CO₂ was about 280 ppm before industry and is about 420 ppm today.
By how many ppm has it risen?
Enter an exact answer, without rounding.
ppm
Subtract.
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A country produces 3 billion tonnes of food and wastes one third.
How many billion tonnes are wasted?
Enter an exact answer, without rounding.
billion t
Divide by 3.
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Global temperature has risen 1.1 °C. The Paris goal is a limit of 2 °C.
How many °C of margin remain?
Enter an exact answer, without rounding.
°C
Subtract.
📝 Lesson quiz · 5 questions
0 / 5
Re-read the lesson, then give it another go.
Question 1 of 5
The Paris Agreement was signed in:
Question 2 of 5
Rising sea levels result from:
Question 3 of 5
Which energy source is low-carbon?
Question 4 of 5
Reducing food waste helps by:
Question 5 of 5
Drip irrigation:
Final Challenge
🏆 10-Question Challenge Quiz
Questions from every topic in this course. Pick an answer for each one, then hit Check My Answers.
0 / 10
💪 Keep practicing — go back through the lessons and retake the quiz!
Q1 · Population Change
In stage 1 of the demographic transition model:
Q2 · Population Change
China’s one-child policy ended in:
Q3 · Migration
Which is both a benefit and a cost for origin countries?
Q4 · Migration
Net migration is positive when:
Q5 · Development
Which pair of indicators together give a better picture than GDP alone?