DSE Economics — National Income and GDP Prep Guide (for tutors) | Four expenditure components, deflate before comparing, five limits with local examples

2026-11-05

Tutor lesson-prep guides · Secondary Economics

Students can chant consumption plus investment plus government spending plus net exports, then read nominal growth of 7 percent against 10 percent inflation as better living. This lesson separates nominal, real and per head with one set of numbers.

Objectives — Students can: (1) combine C, I, G and net exports into a GDP of 1870 billion; (2) deflate a nominal 1870 billion by an index of 110 to a real 1700 billion and compute growth of 3.0 percent; (3) state five limits of GDP, each with a Hong Kong example.

01 Prerequisites (3-minute check)

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

Skill	Quick check	Pass mark
Factors of production	Which four factors does production require?	Land, labour, capital and entrepreneurship
Domestic versus national	Whose production does GDP count, and where?	It counts by territory, whatever the producer nationality
Price indices	When prices rise, what happens to what a fixed sum buys?	It buys less, so nominal values must be deflated

02 Lesson flow (45 minutes)

Time	Stage	Tutor does	Student does
0-5 min	Prior knowledge check	Ask the three prior questions and write the four letters on the board	Answer orally and copy any wrong item once
5-17 min	Act one: four components	Fill each figure, stressing that net exports can be negative	Copy the sum and label the largest component
17-30 min	Act two: nominal is not real	Deflate 1870 billion by 110 and compute growth	Compute once and contrast with nominal growth
30-40 min	Act three: per head and five limits	Divide by 7.5 million, then walk the five limits	Compute once and give one example per limit
40-43 min	One-sentence summary	Ask for one sentence on whether higher GDP means a better life	Answer orally; tutor corrects only wording
43-45 min	Exit check	Hand out three items and collect them	Work alone with books closed

03 Teaching script (read it out)

Scene 1: Act one: net exports can be negative

GDP = C + I + G + (X minus M) = 1200 + 450 + 300 + (520 minus 600) = 1870 billion.
Net exports of -80 billion are negative, which is normal for Hong Kong and not an arithmetic slip.
Consumption is 64.2 percent of the total, so a question asking for the largest component needs that proportion, not just the word consumption.
Inventory changes count as investment; resale of an existing flat does not, because nothing new was produced.

Ask students to repeat: net exports can be negative, and second-hand deals are excluded.

Scene 2: Act two: nominal, real, then growth

Nominal GDP is 1870 billion and the deflator is 110, so real GDP is 1870 divided by 1.10, which is 1700 billion.
Against last year real 1650 billion, growth is 3.03 percent, about 3.0 percent.
Nominal alone rose from 1,700 to 1870, which looks like 10 percent but is partly prices.
The order never changes: deflate, compare, and only then discuss living standards.

Ask students to repeat: deflate to real, then compute growth, then talk about living standards.

Scene 3: Act three: per head and five limits

GDP per head is 1870 billion divided by 7.5 million people, about 249,333 dollars.
Five limits, each with a local example: non-market output such as housework and volunteering is excluded; the underground cash economy is excluded; pollution and congestion costs are not deducted; income distribution is invisible; leisure and product quality are not captured.
So GDP can rise while everyone works longer hours, and any answer on living standards must say so.

Ask students to repeat: GDP counts output, not distribution, not costs, not leisure.

04 Question types and worked steps

Type	Example	Steps	Answer
Expenditure calculation	C 1200, I 450, G 300, X 520, M 600	Add all four, keeping net exports signed	1870 billion
Deflate nominal	Nominal 1870, deflator 110	Divide by the index, multiply by a hundred	1700 billion
Growth rate	Real from 1650 to 1700	Difference over last year, times a hundred	3.03 percent
Limits essay	Does higher GDP mean a better life?	Five limits with examples, then a conclusion	Five sentences plus one judgement

Sanity check (teach this): Three read-backs: (1) with negative net exports GDP must be below C plus I plus G; (2) real is below nominal whenever the index exceeds 100; (3) 249,333 dollars a year is about 20,778 a month, so a monthly figure in the hundreds of thousands means the population was not divided out.

05 Independent practice (3 questions)

Question	Answer	What to watch
C 800, I 300, G 200, X 400, M 450. Find GDP.	1,250	Check the negative sign and whether government spending was included
Nominal up 7 percent, prices up 10 percent. What happens to real output?	It falls by about 2.7 percent	Check 1.07 divided by 1.10 rather than 7 minus 10
Why is housework excluded from GDP?	There is no market transaction, so it cannot be valued	Check whether non-market is named rather than unimportant

06 Common mistakes and what to say

Mistake	Student writes	Say this
Net exports made positive	GDP is 1,200 plus 450 plus 300 plus 80	When imports exceed exports net exports are negative.
Nominal growth read as real	GDP rose 10 percent, so living standards rose 10 percent	Deflate first.
Population not divided out	GDP per head is 187 billion	Divide by 7.5 million to get about 249,000.
Limits left vague	GDP is inaccurate	Name them: non-market output, underground economy, pollution, distribution, leisure.

07 Homework (paper, section and question numbers)

Redo this chapter — Redo the three items, formula first
Demand, supply and elasticity — Use elasticity to explain how net exports respond to an exchange rate move
Economics chapter index — Pick one more chapter and write figures only

08 Exit check (last 5 minutes)

Question	Answer	Decision
C 1200, I 450, G 300, net exports -80: GDP?	1870 billion	Error: treating net exports as plus eighty
With a deflator of 110, what is real GDP?	1700 billion	Error: multiplying by 1.1 instead of dividing
Name three things GDP misses	Housework and other non-market output, the underground economy, pollution and leisure	Error: answering only that it is inaccurate

09 Tutor FAQ

Which year is this for?

Mainly S4, and the base for S5 national income determination.

Is 45 minutes enough for five limits?

Yes, because two are taught in depth and students supply examples for the rest.

Is there a companion worksheet?

Three practice items with answers on the page, plus the elasticity chapter.

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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.