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Demography and Population Change Class 8 Notes

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Social ScienceCBSE Class 8 · Dynamics of Population

Demography, Population Change and Demographic Transition: Class 8 Notes and Questions

Updated 17 October 2026 · Fact-checked

Demography studies the size, structure and change of human population. A country's population changes through births, deaths and migration. Birth rate and death rate are per 1,000 people; replacement-level fertility is 2.1 children per woman. Countries pass through three stages of demographic transition: high birth and death rates, falling death rate with high birth rate, then falling birth rate.

Notice the green gap: it is small in Stage 1, widest in Stage 2 when deaths fall first, and narrows in Stage 3 as births fall.

Illustration drawn for QuestionBuddy.

Understand Demography, Population Change and Demographic Transition

What is demography? The study of the human population: its size, its structure and composition (age, sex, education, occupation, religion), and its pattern and trend over time, as changed by births, deaths and migration. Governments use it to plan schools, hospitals, roads, housing, water, energy and waste services; more children mean more schools, more elderly people mean more healthcare, and a young working-age population means a need for jobs. Businesses use it to understand customers. The census, in India generally conducted every 10 years, is the official count of people in a country and collects information on age, gender, marital status, education, languages, religion, family size, occupation and income.

Population at a glance (NCERT). In 2023 India surpassed China as the world's most populous country; Indians are around 17 per cent of the world's people. World population grew from 2.5 billion in 1950 to 8.2 billion in 2025, with 9.7 billion expected by 2050; according to UN projections it will peak at about 10.3 billion by the mid-2080s and then decline gradually. Growth since 1950 reflects medical advances (antibiotics, vaccines, oral rehydration solution), better water and sanitation and fewer child deaths. Regional population in 2025: Asia 4.8 billion, Africa 1.5 billion. China, Japan and Italy are seeing shrinking populations; India is still growing; some African nations such as Nigeria and Ethiopia grow rapidly. From NCERT's graph, India's population was about 361 million in 1951 and about 1,460 million in 2025.

What determines a country's population? Four indicators.
1. Birth rate: live births per 1,000 population in a year.
2. Fertility rate: the average number of children a woman has in her lifetime. A rate of 2.1 is the replacement level; above 2.1 the population tends to grow, below 2.1 it may shrink. (NCERT asks students to think about why it is 2.1 and not 2.)
3. Death (mortality) rate: deaths per 1,000 people in a year. Lower rates indicate better healthcare and nutrition. NCERT: India's child mortality (deaths under five per 1,000 live births) fell from 271 in 1950 to 28 in 2023, and life expectancy at birth rose from about 30 years at independence to 70 years in 2024.
4. Migration: movement of people within or outside a country. People migrate for jobs, education, or because of disasters or instability. Cities like Delhi, Mumbai and Bengaluru grew through migration, which can strain water, housing and transport.

Falling fertility. India's fertility rate fell from 5.7 in 1950 to 1.9 in 2025 (below replacement), with campaigns such as 'Hum do humare do' from 1952. Factors: girls' education, women in formal jobs and later marriage, urbanisation and a high cost of living. In NCERT's table, states with higher women's literacy tend to have lower fertility (for example Bihar: fertility 3.0, women's literacy 55 per cent; Delhi: 1.6 and 83.7 per cent).

China's example. The One-Child Policy (1979) cut fertility from 7.5 in 1963 to 1 in 2025; China's population peaked at 1.43 billion in 2022 and is projected to be 1.31 billion by 2050, while the share above 65 rises from 14 per cent (2023) to 26 per cent (2050). The policy ended in 2015 and up to three children are allowed, yet fertility remains below replacement.

Stages of demographic transition.

  • Stage 1: high birth and death rates, so growth is slow; India from 1901 to 1921.
  • Stage 2: death rate falls (better healthcare) while birth rate stays high, causing rapid growth; India after 1951.
  • Stage 3: death rate low and birth rate falls (urbanisation, income, education, women's work); growth slows and population may start shrinking, as in Italy, Japan and South Korea. In India fertility began declining after the mid-1980s and is now below replacement.

Demography, Population Change and Demographic Transition: key facts

Birth rate and death rate
Birth rate = live births in a year / population x 1,000 | Death rate = deaths in a year / population x 1,000
Both are per 1,000 people.
Replacement-level fertility
  • 2.1 children per woman
  • above 2.1 population grows
  • below 2.1 it may shrink
NCERT's definition.
Four indicators
  • Birth rate
  • Fertility rate
  • Death rate
  • Migration
What determines population.
NCERT numbers for India
Child mortality271 per 1,000 (1950) to 28 (2023)
life expectancy30 years to 70 years (2024)
fertility5.7 (1950) to 1.9 (2025)
Quote with years.
Stages of transition
Stage 1high birth, high death
Stage 2falling death, high birth
Stage 3low death, falling birth
India: 1901-21, after 1951, after mid-1980s.

How to answer Demography, Population Change and Demographic Transition questions

Questions ask for definitions of demographic terms, numerical rates per 1,000, reasons for falling fertility, push and pull factors of migration, and the stage of a country in the demographic transition.

  1. 1For rates, write the formula, substitute, and state the unit 'per 1,000'.
  2. 2For stage questions, compare the birth and death rates and name the stage.
  3. 3For reasons, use NCERT's list: education of girls, jobs, urbanisation, cost of living.
  4. 4For India, cite the three numbers: 5.7 to 1.9, 271 to 28, 30 to 70.
  5. 5Label any derived value as derived (for example natural increase = birth rate - death rate).

Demography, Population Change and Demographic Transition in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Calculating a birth rate and a death rate

Suppose in a town of 50,000 people there were 900 live births and 400 deaths in one year (hypothetical figures).

Find the birth rate and death rate, and the difference (a derived figure).

Try it first, then show the solutionSolution
  1. Birth rate = 900 / 50,000 x 1,000 = 18 per 1,000.
  2. Death rate = 400 / 50,000 x 1,000 = 8 per 1,000.
  3. Difference = 18 - 8 = 10 per 1,000 (derived by us).

Answer: Birth rate = 18 per 1,000; death rate = 8 per 1,000. The birth rate exceeds the death rate by 10 per 1,000, so ignoring migration the town's population is growing (this difference is our own derived measure, not defined in the chapter). Check: 18 x 50 = 900 and 8 x 50 = 400.

Memory hook: Rates count per thousand, not per head.

Tricks to remember Demography, Population Change and Demographic Transition

Short memory aids. Say each one aloud once, then use it on a question the same day.

  • B-F-D-M

    Birth rate, Fertility rate, Death rate, Migration.

    Use it when: Indicators of population change.

  • Stage 1-2-3

    Both high; death falls first; birth falls later.

    Use it when: Demographic transition.

  • 2.1 for replacement

    Above 2.1 grows, below 2.1 shrinks.

    Use it when: Fertility rate rule.

Demography, Population Change and Demographic Transition: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Replacement level · 1 mark · MCQBoard level

The replacement-level fertility rate is:
(a) 1.0
(b) 1.9
(c) 2.1
(d) 3.0

Try it first, then show the solutionSolution
  1. NCERT: 2.1 children per woman replaces the parents in the population (1 mark).

Answer: (c) 2.1

Example 2: Rates calculation (3 marks) · 3 marks · Short answerHarder board level

A district has a population of 2,40,000. In one year there were 4,320 live births and 1,920 deaths. Find the birth rate and the death rate per 1,000 and say whether births exceed deaths. (3 marks)

Try it first, then show the solutionSolution
  1. Birth rate = 4,320 / 2,40,000 x 1,000 = 18 per 1,000 (1 mark).
  2. Death rate = 1,920 / 2,40,000 x 1,000 = 8 per 1,000 (1 mark).
  3. 18 is greater than 8, so births exceed deaths and (leaving out migration) the population grows (1 mark).

Answer: Birth rate = 4,320 / 2,40,000 x 1,000 = 18 per 1,000. Death rate = 1,920 / 2,40,000 x 1,000 = 8 per 1,000. Births exceed deaths, so apart from migration the district's population is growing. Check: 2,40,000 / 1,000 = 240; 240 x 18 = 4,320 and 240 x 8 = 1,920.

Example 3: Assertion-reason: fertility and girls' education · 1 mark · Assertion-reasonHarder board level

Assertion (A): Fertility rates tend to fall as girls' education improves.
Reason (R): Educated women are more likely to take formal jobs, marry later and have fewer children.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.

Try it first, then show the solutionSolution
  1. NCERT gives this reasoning (1 mark).

Answer: (a) Both A and R are true, and R is the correct explanation of A.

Example 4: Stages of transition (5 marks) · 5 marks · Long answerHarder board level

Explain the three stages of demographic transition and show where India stood at different times. (5 marks)

Try it first, then show the solutionSolution
  1. Stage 1: both rates high, slow growth; India 1901-1921 due to poor healthcare and low literacy (2 marks).
  2. Stage 2: death rate falls, birth rate high, rapid growth; India after 1951 (1 mark).
  3. Stage 3: death rate low, birth rate falls due to urbanisation, income, education and women's work; growth slows or population shrinks (1 mark).
  4. India's fertility began declining after the mid-1980s and is now below replacement; Italy, Japan and South Korea show shrinking (1 mark).

Answer: In Stage 1 birth and death rates are both high, so population growth is slow or stagnant; India was in this stage from 1901 to 1921, with poor healthcare and low literacy. In Stage 2 death rates fall because of better healthcare while birth rates stay high, causing rapid growth; India's population grew rapidly after 1951. In Stage 3 death rates stay low and birth rates fall because of urbanisation, higher income, education and more women working, so growth slows; if fertility falls a lot, the population may shrink, as in Italy, Japan and South Korea. In India fertility began declining after the mid-1980s and is now below replacement level.

Example 5: Case: China's policy · 4 marks · Case-basedHOTS / competency

Read the case and answer.

NCERT records that China introduced a One-Child Policy in 1979 to prevent shortages of food, jobs and housing. Its fertility rate dropped from 7.5 in 1963 to 1 in 2025. The population peaked at 1.43 billion in 2022 and is projected to fall to 1.31 billion by 2050, while the share of those above 65 is expected to rise from 14 per cent in 2023 to 26 per cent in 2050. The policy ended in 2015, but fertility remains below replacement level.

(i) By how many percentage points is the elderly share expected to rise between 2023 and 2050? (1)
(ii) By how many billion is the population expected to fall from the 2022 peak to 2050? (1)
(iii) Explain two economic effects of such a change. (2)

Try it first, then show the solutionSolution
  1. (i) 26 - 14 = 12 percentage points (1 mark).
  2. (ii) 1.43 - 1.31 = 0.12 billion, that is, 12 crore (1 mark).
  3. (iii) Fewer younger workers for farms, factories and offices may slow economic growth; more elderly raise demand for healthcare and pensions (2 marks).

Answer: (i) 26 - 14 = 12 percentage points. (ii) 1.43 - 1.31 = 0.12 billion (12 crore) fewer people. (iii) With more people retiring and fewer young workers, there may be a shortage of workers in farms, factories and offices, slowing economic growth, and a larger elderly population needs more healthcare and pension support.

Where students lose marks in Demography, Population Change and Demographic Transition

The slips examiners see most often, and what to write instead.

  • Mistake: Computing a rate per 100

    Percentage habit.

    Wrong working

    Birth rate = 900 / 50,000 x 100 = 1.8.

    Right working

    Birth rate is per 1,000: 900 / 50,000 x 1,000 = 18.

    Do this: Always multiply by 1,000 and write the unit.

    Usually costs: 1-2 marks.

  • Mistake: Confusing birth rate and fertility rate

    Both relate to births.

    Wrong working

    Fertility rate is the number of births per 1,000 people.

    Right working

    Fertility rate is the average number of children per woman; birth rate is births per 1,000 people.

    Do this: Birth rate per 1,000 people; fertility per woman.

    Usually costs: 1 mark.

  • Mistake: Saying a rate of 2 is replacement

    Parents replaced by two children.

    Wrong working

    Replacement level is 2.0.

    Right working

    NCERT gives 2.1.

    Do this: Remember 2.1.

    Usually costs: 1 mark.

Exam tips

  • Show formula, substitution, answer and unit for rate questions, and check by reverse multiplication.
  • Memorise India's 3 headline changes: fertility, child mortality, life expectancy.
  • Identify the stage of transition by comparing the two rates.
  • Mention the source and year whenever you quote NCERT's statistics.

Practice questions on Demography, Population Change and Demographic Transition

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

  1. Q1 · 1 mark · MCQBoard level

    Which of the following is an official count of the people living in a country?
    (a) Survey
    (b) Census
    (c) Projection
    (d) Pyramid

    Hint

    Done every 10 years in India.

    Answer

    (b) Census

  2. Q2 · 2 marks · Very short answerBoard level

    Define fertility rate and explain what a rate of 2.1 means. (2 marks)

    Hint

    Average children per woman.

    Answer

    The fertility rate is the average number of children a woman would have in her lifetime. A rate of 2.1 is called the replacement level because it is the number of children needed to replace the parents; above it the population tends to grow and below it the population may shrink.

  3. Q3 · 3 marks · Short answerHarder board level

    A village of 8,000 people has 160 births and 56 deaths in a year. Calculate the birth rate and death rate per 1,000. (3 marks)

    Hint

    160 / 8,000 x 1,000.

    Answer

    Birth rate = 160 / 8,000 x 1,000 = 20 per 1,000. Death rate = 56 / 8,000 x 1,000 = 7 per 1,000. Check: 8,000 / 1,000 = 8; 8 x 20 = 160 and 8 x 7 = 56.

  4. Q4 · 1 mark · Assertion-reasonHarder board level

    Assertion (A): Concentration of migrants in big cities can strain resources.
    Reason (R): A very large population in a limited area puts pressure on water, air, land, transport and housing.
    (a) Both A and R are true, and R is the correct explanation of A.
    (b) Both A and R are true, but R is not the correct explanation of A.
    (c) A is true, but R is false.
    (d) A is false, but R is true.

    Hint

    What happens when many people crowd in?

    Answer

    (a) Both A and R are true, and R is the correct explanation of A.

  5. Q5 · 5 marks · Long answerHOTS / competency

    India's fertility rate fell from 5.7 in 1950 to 1.9 in 2025, while child mortality fell from 271 to 28 per 1,000 between 1950 and 2023. Explain how these two trends together shaped India's population growth through the three stages, and name two factors behind each. (5 marks)

    Hint

    Death rate fell first; fertility followed; growth first speeded up and then slowed.

    Answer

    After 1951 healthcare, vaccines, sanitation and nutrition cut deaths, especially of children (271 to 28 per 1,000), while births stayed high, so the population grew rapidly: Stage 2. Later, as girls' education and women's formal jobs spread, marriage was later, urbanisation raised living costs and the family size norm shrank, so fertility fell from 5.7 to 1.9, below the replacement level of 2.1. Falling fertility slows growth, moving India into Stage 3, although the population still grows for now because of its large young population. The two trends together explain the speeding up and then slowing down of India's growth.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

  1. 1.What is demography?Show answer

    The study of the size, structure and changes of the human population.

  2. 2.In which year did India become the world's most populous country, as per NCERT?Show answer

    2023.

  3. 3.What is life expectancy?Show answer

    The average number of years a newborn is expected to live under present conditions.

  4. 4.Name one push factor of migration mentioned.Show answer

    Natural disasters or political instability (also lack of jobs).

  5. 5.When was the One-Child Policy introduced in China?Show answer

    1979.

Demography, Population Change and Demographic Transition: frequently asked questions

What is the difference between birth rate and fertility rate?

Birth rate is the number of live births per 1,000 people in a year; fertility rate is the average number of children a woman would have in her lifetime.

Why is the population of Japan and China shrinking?

Low fertility rates, below replacement level, mean fewer births than deaths over time, as NCERT notes for China, Japan and Italy.

What are the three stages of demographic transition?

Stage 1: high birth and death rates; Stage 2: falling death rate with high birth rate; Stage 3: low death rate with falling birth rate.