DSE Geography | Population Ageing Lesson-Prep Guide (Tutor Edition)

DSE Geography | Population Ageing Lesson-Prep Guide (Tutor Edition) | Dependency Ratio, Pyramids and Policy

2026-11-02

Tutor lesson-prep guides · Secondary Geography

Students see a narrow base and say falling births, but cannot say how many workers carry each dependent. This lesson turns the shape of a pyramid into one comparable number.

Objectives — Students can: (1) compute the total dependency ratio from three age groups and interpret it; (2) read a pyramid and match narrow and bulging bands to past events; (3) evaluate three ageing policies with costs and benefits.

01 Prerequisites (3-minute check)

If any of these fails, fix it before the lesson starts.

Skill	Quick check	Pass mark
Ratios	How a ratio becomes a percentage	Multiply by 100
Age groups	Which ages count as working age	15 to 64
Averages	Mean versus median	The median takes the middle value

02 Lesson flow (60 minutes)

Time	Stage	Tutor does	Student does
0-8 min	Three groups	Young, working, old	Sort the data
8-20 min	Dependency ratio	(Young + old) over working	42.9%
20-32 min	Pyramid reading	Narrow base, bulging middle	Name two past events
32-44 min	Impacts	Labour, health care, pensions	One consequence each
44-54 min	Policy	Births, migration, longer careers	Costs and benefits
54-60 min	Exit check	Three questions, marked at once	Done independently

03 Teaching script (read it out)

Scene 1: The dependency ratio: one fraction for the burden

With 10% young, 20% old and 70% of working age, the total dependency ratio is (10 + 20) / 70 x 100 = 42.9%, meaning about 43 dependants per hundred workers.
Of 7.5 million people, roughly 1.50 million are elderly; if 6% need long-term care, that is about 0.09 million people.
A rising ratio does not automatically mean a weaker economy; productivity and participation matter too.

Ask the student: if the elderly share rises from 20% to 25% with a fixed working group, the ratio becomes 50%.

Scene 2: The pyramid: shape is history

A narrow base means falling births, a bulging middle means a baby boom now in mid-life, and a widening top means longer lives.
The median age rises from 44 to 52, up 8 years, while life expectancy rises from 83.0 to 86.5.
A low birth, low death, long life society sits in stage four, so the pyramid looks like a lantern rather than a triangle.

Ask the student: a triangular pyramid belongs to which stage of the demographic transition (one or two).

Scene 3: Policy: three roads, each with a price

Encouraging births: cash allowances and childcare, slow to show, costly, and hard to reverse falling fertility.
Admitting migrants: fills the working gap at once but pressures housing and integration, and is politically sensitive.
Extending working and retirement ages: raises participation but burdens manual workers unless retraining follows.
Health and elderly care: community plus residential care, a cost that rises regardless.

Ask the student: why birth incentives cannot shift the ratio quickly (a baby needs fifteen years to enter the workforce).

04 Question types and worked steps

Type	Example	Steps	Answer
Calculation	Total dependency ratio	(Young + old) over working x 100	42.9%
Calculation	Number of elderly	Total population x elderly share	1.50 million
Interpretation	Population pyramid	Compare base, middle and top widths	Shape maps to births and deaths
Essay	Policy evaluation	Policy, benefit, limitation	One limitation per policy

Sanity check (teach this): The denominator is the working-age group, not the total population, and the three shares must add to 100%. A ratio above 100% means more dependants than workers and needs data support. A share and a headcount are different answers, so read what the question asks.

05 Independent practice (3 questions)

Question	Answer	What to watch
Total ratio with 10% young and 20% old	42.9%	Add, then divide by the working share
Elderly count within 7.5 million	1.50 million	Multiply by the share
What a narrow pyramid base shows	Falling birth rate	Look at the bottom two bands

06 Common mistakes and what to say

Mistake	Student writes	Say this
Using total population as denominator	Ratio computed as 30.0%	The divisor is the working-age group.
Shares that do not add to 100%	Dropping the young group	Add the three groups first.
Mixing a share with a headcount	Answering 200 thousand for 20%	Multiply the share by the total.
Listing only benefits	Essay praises migration only	Give one limitation per policy to reach the top band.

07 Homework (paper, section and question numbers)

Secondary geography chapter index — All chapters and practice
All lesson-prep guides — Compare other subjects

08 Exit check (last 5 minutes)

Question	Answer	Decision
Ratio for 10% and 20%	42.9%	All three right: move to urbanisation
Elderly count in 7.5 million	1.50 million	One wrong: reteach proportion
Meaning of a narrow base	Falling births	Two or more wrong: return to act two

09 Tutor FAQ

Is a higher dependency ratio always worse?

No; productivity, participation and social protection all matter.

Why use a pyramid rather than a single ratio?

It shows age and sex structure, while a ratio gives only one total.

Does ageing come more from births or from longevity?

Both, but in recent decades low fertility weighs more.

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A TutorZone lesson-prep guide. Written by the TutorZone team; questions and lesson flow are original and are not taken from any school or publisher material.