Key Stage 3 geography · Human geography

KS3 population: growth, density and change for parents

In Key Stage 3, pupils study where people live and why, how populations grow or shrink, and what the shape of a country’s population means for its future. They learn to calculate and interpret data such as density, birth rates and death rates, and to read population pyramids. It matters because population affects housing, schools, jobs and healthcare, and the topic builds the data skills pupils need in GCSE geography.

Population, explained

The world’s population passed 8 billion in 2022, but people are not spread evenly. Population distribution describes where people live, and population density measures how crowded a place is, in people per square kilometre. Pupils learn that people cluster where living is easier: on flat land, in mild climates, near fresh water, fertile soil, jobs, trade routes and resources. Few people live in deserts, high mountains, polar regions or dense rainforests. A high density does not tell you whether a place is rich or poor, since it can describe a wealthy city and a crowded poor region alike.

A population changes in two ways: natural change and migration. Natural change is the birth rate minus the death rate, both given per 1,000 people per year. If births are higher than deaths, the population grows naturally. Migration is the movement of people, and net migration is the difference between those who arrive (immigrants) and those who leave (emigrants). Pupils explore push factors, such as lack of jobs or conflict, and pull factors, such as better services or safety, that cause people to move.

Population pyramids show the number of people at each age, split by male and female. A pyramid with a wide base and narrow top, typical of countries with a high birth rate and shorter life expectancy, shows a young population. A pyramid with straighter sides, narrower at the base and with many people in the middle and older age groups, shows a low birth rate and long life expectancy: an ageing population. Pupils learn to describe the pyramid and then explain what it implies, such as the need for more primary schools in one country and more care and pensions in another.

The demographic transition model describes how birth and death rates tend to change as a country develops. In stage 1 both are high and the population stays small and fairly steady. In stage 2 death rates fall because of better food, water and medicine while birth rates stay high, so population grows fast. In stage 3 birth rates fall, so growth slows, and in stage 4 both are low and population is stable or growing slowly. Some versions add a fifth stage, in which birth rates fall below death rates. Teachers present it as a model, meaning a simplified pattern that doesn’t fit every country perfectly.

Schools choose place-based examples to show the model in use, such as a country with a very young population, one with an ageing population and one that has tried to influence its population size through policy. Pupils might compare Japan with Niger, or consider China’s one-child policy, which operated for about 35 years until it was replaced by a two-child policy in 2016. Teachers expect pupils to use figures, compare places and give reasons, not just opinions, which is why this topic is a good place to practise geographical data skills.

Words your child will hear

Population density: The average number of people living in each square kilometre.
Birth rate: The number of live births each year for every 1,000 people.
Death rate: The number of deaths each year for every 1,000 people.
Natural change: The birth rate minus the death rate.
Net migration: The number of people arriving in a place minus the number leaving.
Life expectancy: The average number of years a person is expected to live.
Dependent population: People too young or too old to work, such as children and retired people.

What the National Curriculum says

The programme of study for Key Stage 3 says:

Pupils should be taught to understand, through the use of detailed place-based exemplars at a variety of scales, the key processes in physical and human geography
Human geography relating to: population and urbanisation; international development; economic activity in the primary, secondary, tertiary and quaternary sectors; and the use of natural resources
Pupils should develop greater competence in using geographical knowledge, approaches and concepts [such as models and theories] and geographical skills in analysing and interpreting different data sources.

Objectives from the National Curriculum in England, © Crown copyright, used under the Open Government Licence v3.0.

A worked example: density and natural change

A region has 3,000,000 people living in 1,500 square kilometres. Its birth rate is 20 per 1,000 and its death rate is 8 per 1,000. Find the population density and the natural change, and say what will happen to the population.

Find the density by dividing the population by the area. Check the units: people per square kilometre.
```
3,000,000 ÷ 1,500 = 2,000
2,000 people per km²
```
Find the natural change rate by subtracting the death rate from the birth rate. Both are per 1,000 people.
```
20 − 8 = 12 per 1,000
```
Turn the rate into a percentage. 12 per 1,000 is 12 ÷ 1,000 = 0.012, which is 1.2% a year.
Turn the rate into a number of people. 3,000,000 people is 3,000 groups of 1,000, and each group adds 12 people, so multiply 3,000 by 12.
```
3,000,000 ÷ 1,000 = 3,000
3,000 × 12 = 36,000
about 36,000 more people a year
```
Interpret the result. Births exceed deaths, so the population is growing naturally. A falling death rate with a birth rate that is still fairly high is typical of the middle stages of the demographic transition model. The figure leaves out migration, so the real change could be higher or lower.

The density is 2,000 people per km². Natural change is +12 per 1,000, or 1.2% a year, which is about 36,000 extra people a year. The population is growing, before any effect of migration is counted.

Common mistakes and how to help

Assuming a high population density means a country is overcrowded or poor

Density sounds like a measure of pressure and hardship.

What helps: Density is an average and says nothing about wealth. Compare a small, rich, densely populated place with a large, poor, thinly populated one, and ask what else you would need to know.

Confusing the growth rate with the number of people

The world’s population is still rising, so pupils assume growth is speeding up.

What helps: The population can keep rising even when the rate of growth is slowing, just as a car can keep moving forward while braking. Check whether a question asks about the rate or the total.

Treating natural change as the whole story

Birth and death rates are the easiest figures to calculate.

What helps: Migration can matter as much, especially for cities and some countries. Always ask whether a figure includes it.

Believing every country follows the demographic transition model in exactly the same way

The model is drawn as a single neat graph.

What helps: It is a generalisation based on how many countries changed. Some changed much faster, others have been affected by war, disease or government policy.

How to help at home

Draw your own family pyramid. List the ages of relatives across several generations, group them in 10-year bands and draw horizontal bars. Does the shape look like a pyramid, a column or an inverted shape? Ask what that might say about a whole country.
Practise density with a map. Pick two areas on a map, estimate their area and use a given population to work out density. Using round numbers, your child can say which is more crowded and by how many times.
Talk about push and pull. Ask whether anyone in your family or friends has moved to a new town or country, and what pushed them away and pulled them towards the new place. Real stories bring the factors to life.
Check a data source. When a news item quotes population figures, ask who produced them, how recent they are and what they leave out. This is an important habit in geography and elsewhere.
Compare two countries in an atlas. Choose two countries from the data tables in an atlas and compare birth rate, death rate and life expectancy. Which demographic transition stage might each be in, and what is the evidence?

Builds on

Key Stage 2: Climate zones, biomes and vegetation belts
Key Stage 2: Rivers and the water cycle
Key Stage 2: Mountains
Key Stage 2: Volcanoes and earthquakes
Key Stage 2: Settlements and land use
Key Stage 2: Economic activity and trade
Key Stage 2: Natural resources