Population density, distribution and structure
Interpret population density and distribution, read population pyramids, and compare population structures using the syllabus income groups.
This original StudyForA sequence supports Cambridge IGCSE Environmental Management 0680 Topics 1–4 for exams in 2027, 2028 and 2029. Named local examples are chosen by the learner and centre; verify current conditions and local context with reliable sources. It is not a Cambridge paper, official grade or complete course.
Before you begin
- Use the 2027–2029 syllabus and check your exam year and centre's entry arrangements. Topics 1–4 are taught on this page; Topics 5–7 are still being built.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What does population distribution describe?
What you will learn
- Interpret population density and distribution, read population pyramids, and compare population structures using the syllabus income groups.
- Use evidence from an unfamiliar case to compare options and justify a context-sensitive judgement.
Describe where people live
Sparsely populated places contain few people; densely populated places contain many. Population density is the number of people living in an area, usually measured in people per km².
Population distribution describes how people are spread over an area. Density is a number per unit area; distribution is the spatial pattern. A place can have a high average density but still contain unevenly populated areas.
Interpret population pyramids
A population pyramid represents age structure and the female and male population. Use the base and upper age groups to describe the young and elderly dependent population, and the working population in between.
Read the scale and compare age groups before explaining a pattern. A pyramid describes structure at a time; it does not by itself explain why the population has that structure.
Use income groups carefully
The syllabus uses World Bank categories: low-income countries (LICs), middle-income countries (MICs) and high-income countries (HICs). Use the category supplied for the question and the relevant time period.
Compare the population structures shown in the data. Some LIC examples may have a larger young population and some HIC examples a larger elderly population, but country categories are broad and the evidence in each question should guide the comparison.
Sources for this lesson
Pause and explain
Which data does a population pyramid show?
Worked example
A population pyramid has a broad base and a narrow top. Describe one feature of its structure and explain what additional data you need before comparing it with another country.
Show the worked solution
- The broad base indicates a relatively large younger population compared with older age groups, subject to the scale shown.
- The narrow top indicates fewer people in the oldest age groups than at the base.
- For a fair comparison, use the age and sex scales, population totals or percentages and the same year or time period.
Answer A broad base suggests a larger young population and a narrow top fewer people at older ages. Compare scales, proportions and time periods before drawing a conclusion.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
A town has 240 000 residents across 120 km². Calculate population density and explain how this differs from distribution.
Give me a hint
Divide the population by area, then state what the resulting number cannot show.
Compare my reasoning
- Population density is population divided by area: 240 000 ÷ 120 = 2 000 people per km².
- The value gives an average number per unit area.
- It does not show how residents are spread within the town; a distribution map could show clustering or sparsely populated districts.
The average density is 2 000 people per km². A distribution map is needed to show where people live within that area.
Look for these in your work
- Calculation correct
- Unit included
- Density and distribution distinguished
A population pyramid has a high proportion of children and a relatively small older population. Identify the likely dependent groups and explain one service-planning implication without assuming a cause.
Give me a hint
Describe the age structure first; use evidence before claiming why it exists.
Compare my reasoning
- Children are part of the young dependent population; the older group is the elderly dependent population.
- A large young group may increase demand for schools and child health services.
- The pyramid describes structure but does not by itself explain the cause; compare birth, death and migration data before making that claim.
The structure suggests high demand for services for young people, but further data are needed to explain why the age pattern exists.
Look for these in your work
- Dependent group identified
- Service implication follows from structure
- Cause not inferred without evidence
Two countries are labelled LIC and HIC in a question. Compare their supplied population pyramids and explain why the labels alone are insufficient.
Give me a hint
Use the actual age and sex shares, scale and year shown in each pyramid.
Compare my reasoning
- Describe the proportion of young, working and elderly groups in each pyramid using its scale.
- Compare female and male structure and note similarities or differences supported by the data.
- The income labels provide context, but population patterns vary; the pyramid data and time period must support the conclusion.
Use the pyramids to compare population structure. LIC/HIC categories provide context, not a substitute for reading the supplied evidence.
Look for these in your work
- Age structure compared
- Sex data considered
- Labels not treated as proof
Common mistakes
- Treating density and distribution as the same measure
- Reading a population pyramid without checking the scale
- Assuming every LIC or HIC has the same population structure
- Treating income groups as fixed measures of people's worth
What can you explain now?
What is population density?
Compare with the explanation
The number of people living in an area, usually per km²
The correct answer is “The number of people living in an area, usually per km²”. The alternatives “How people are spread over an area” and “The number of people who migrate each year” do not match the syllabus concept. Interpret population density and distribution, read population pyramids, and compare population structures using the syllabus income groups.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Define density and distribution, interpret population pyramids and compare LIC, MIC and HIC structures using the supplied evidence.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.