EconomicsICSE Class 10 · Demand and Supply

Movement and Shift of Demand and Supply Curves, with Determinants (ICSE Class 10)

Updated 17 October 2026 · Fact-checked

A movement along a curve (extension or contraction) is caused only by a change in the commodity's own price. A shift of the curve (increase or decrease) is caused by other determinants such as income, tastes, input costs or technology, at the same price. For demand, an increase moves the curve right; for supply, an increase also moves the curve right.

Understand Movement and Shift of Demand and Supply Curves

Two kinds of change.

Change in quantity demanded or supplied: price changes, the curve stays, we move along it.
Change in demand or supply: some other factor changes, the whole curve moves.

Demand curve.

Cause	Result	Name
Price falls	Move down the curve	Extension of demand
Price rises	Move up the curve	Contraction of demand
Other factor makes buyers want more	Shift right	Increase in demand
Other factor makes buyers want less	Shift left	Decrease in demand

Supply curve.

Cause	Result	Name
Price rises	Move up the curve	Extension of supply
Price falls	Move down the curve	Contraction of supply
Input costs fall, technology improves	Shift right	Increase in supply
Input costs rise, tax imposed	Shift left	Decrease in supply

Determinants of demand. Price of the commodity (movement); income (normal and inferior goods); prices of related goods (substitutes and complements); tastes and fashion; expectations of future prices; population; distribution of income; season, advertising and government policy.

Determinants of supply. Price (movement); prices of inputs; technology; prices of related goods; goals of the firm; number of firms; taxes and subsidies; weather and expectations.

Normal and inferior goods. For a normal good, demand rises with income. For an inferior good (such as coarse grain for a household that becomes richer), demand falls as income rises.

Key tip. Only the commodity's own price causes movement. Every other determinant causes a shift.

Movement and Shift of Demand and Supply Curves: key facts

Movement (own price): Demand: extension price falls
contraction price rises
Supply: extension price rises
contraction price falls
Shift (other factors): Increase = rightward shift | Decrease = leftward shift
Demand determinants: Income
Related goods
Tastes
Expectations
Population
Supply determinants: Input prices
Technology
Taxes and subsidies
Number of firms
Weather

Demand: extension	price falls
contraction	price rises
Supply: extension	price rises
contraction	price falls

How to answer Movement and Shift of Demand and Supply Curves questions

First ask: what changed? If the commodity's own price, it is a movement; if anything else, it is a shift.

1Identify the cause given in the question.
2If the cause is own price, name extension or contraction and the direction along the same curve.
3If the cause is another determinant, name increase or decrease and the shift left or right.
4Check normal or inferior good before deciding the effect of income.
5Draw one diagram with both curves if asked to compare.

Movement and Shift of Demand and Supply Curves 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.

Cold drink in summer

Suppose the price of a cold drink stays ₹20 but a heatwave raises demand from 100 to 160 bottles a day. Another day, the price falls to ₹15 and demand rises along the original curve from 100 to 125.

Which of these is a movement and which is a shift?

Try it first, then show the solutionSolution

Heatwave: demand changes at the same price (100 to 160), so the curve shifts right (increase in demand).
Price cut: change in quantity from 100 to 125 as the price falls, so a movement down the curve (extension of demand).

Answer: Heatwave: shift (increase in demand). Price cut: movement (extension).

Memory hook: Own price: slide; anything else: shift.

Tricks to remember Movement and Shift of Demand and Supply Curves

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

Own price slides, others shift
Only own price causes a movement.
Use it when: Quick test.
E-C and I-D
Extension-Contraction = movement; Increase-Decrease = shift.
Use it when: Terms.
Right = more
Rightward shift means more demand or supply at each price.
Use it when: Direction.

Movement and Shift of Demand and Supply Curves: solved examples

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

Example 1: Identify · 1 mark · MCQBoard level

The price of tea falls and quantity demanded rises from 20 to 30 cups. This is:
(a) increase in demand
(b) extension of demand
(c) decrease in demand
(d) contraction of demand

Try it first, then show the solutionSolution

Own price changed, so movement along the curve; price fell and quantity rose: extension.

Answer: (b)

Example 2: Name the change · 2 marks · Short answerBoard level

Name the change and the direction on the curve: (i) income rises and demand for a normal good rises; (ii) price of a good rises and quantity supplied rises. (2 marks)

Try it first, then show the solutionSolution

(i) Income is another determinant: increase in demand, rightward shift.
(ii) Own price: extension of supply, upward movement along the supply curve.

Answer: (i) Increase in demand (shift right); (ii) extension of supply (movement up).

Example 3: Substitutes and complements · 4 marks · Long answerHarder board level

The price of coffee rises sharply. Explain the effect on the demand for tea (substitute) and on demand for sugar used with coffee (complement). Name the type of change. (4 marks)

Try it first, then show the solutionSolution

Tea becomes relatively cheaper, so more people switch: demand for tea increases (shift right).
Coffee is used less, so less sugar for coffee is needed: demand for sugar decreases (shift left).
In both cases, the price of the commodity itself is unchanged, so these are shifts, not movements.

Answer: Demand for tea shifts right; demand for the complement shifts left.

Example 4: Supply shift numerical · 3 marks · Short answerHarder board level

At ₹20 a firm supplies 200 units. Cheaper raw material allows it to supply 260 units at the same price. Find the per cent change in supply and name the type of change. (3 marks)

Try it first, then show the solutionSolution

Change = 260 − 200 = 60 units.
Per cent = 60 ÷ 200 × 100 = 30%.
Price is unchanged and input cost fell: increase in supply, shift to the right.

Answer: 30% increase in supply; rightward shift.

Example 5: Inferior good · 1 mark · Assertion-reasonHOTS / competency

Assertion (A): When a household's income rises, its demand for coarse grain may fall.
Reason (R): Coarse grain is an inferior good for that household.
(a) Both A and R are true and R explains A
(b) Both A and R are true but R does not explain A
(c) A is true, R is false
(d) A is false, R is true

Try it first, then show the solutionSolution

For inferior goods demand falls as income rises, because people switch to better substitutes.

Answer: (a)

Where students lose marks in Movement and Shift of Demand and Supply Curves

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

Mistake: Calling a price-caused change a shift
Terms confused.
Wrong working
Price falls so demand increases.
Right working
Price falls so quantity demanded extends.
Do this: Use extension/contraction for own price.
Usually costs: 1-2 marks.
Mistake: Shift direction reversed for supply
Costs misread.
Wrong working
Cost rise shifts supply right.
Right working
Cost rise shifts supply left.
Do this: Higher costs mean less supply.
Usually costs: 1 mark.
Mistake: No diagram
Missing visual.
Wrong working
Words only.
Right working
Add a neat diagram with DD and DD1.
Do this: Draw two curves and label.
Usually costs: 1-2 marks.

Exam tips

Use the exact terms extension, contraction, increase, decrease.
Draw DD and D1D1 when you describe a shift.
Always state the cause of the change.

Practice questions on Movement and Shift of Demand and Supply Curves

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

Q1 · 1 mark · MCQBoard level
A rightward shift of the demand curve is called:
(a) extension
(b) contraction
(c) increase in demand
(d) decrease in demand
Hint
Right = increase.
Answer
(c)
Q2 · 3 marks · Short answerBoard level
A fall in price extends demand, whereas a rise in income increases it. Compare the two on cause, movement and effect on the curve. (3 marks)
Hint
Cause and curve.
Answer
Extension is caused by a fall in the commodity's own price and is a movement down the same demand curve. Increase in demand is caused by other factors such as income and the whole curve shifts right.
Q3 · 3 marks · Short answerHarder board level
List any four determinants of supply and state the effect of a tax on supply. (3 marks)
Hint
Costs, technology, tax.
Answer
Input prices, technology, number of firms, taxes and subsidies. A tax raises the cost, reducing supply at each price: the curve shifts left.
Q4 · 4 marks · Long answerHarder board level
Explain, with the help of an example each, how a rise in income affects the demand for a normal good and for an inferior good. (4 marks)
Hint
Normal versus inferior.
Answer
For a normal good, such as a branded shirt, demand increases and the curve shifts right. For an inferior good, such as coarse cereals, demand decreases and the curve shifts left as consumers move to better goods.
Q5 · 4 marks · Long answerHOTS / competency
At ₹50 per unit the quantity demanded is 120. After a successful advertising campaign it becomes 150 at the same price. Later, the price falls to ₹40 and the quantity demanded is 180 (new curve). Name each change and find the per cent change in each. (4 marks)
Hint
First change at the same price; second along the new curve.
Answer
Advertising: (150 − 120) ÷ 120 × 100 = 25% increase in demand (shift right). Price fall: (180 − 150) ÷ 150 × 100 = 20% extension of demand (movement down the new curve).

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.Only cause of movement?Show answer
Own price.
2.Increase in demand shifts?Show answer
Right.
3.Rise in input cost does what to supply?Show answer
Decreases it (shift left).
4.Inferior good and income?Show answer
Demand falls as income rises.
5.Substitute price rises: demand for other good?Show answer
Increases.

Movement and Shift of Demand and Supply Curves: frequently asked questions

What is the difference between movement and shift?

Movement is caused by own price along the same curve; shift is caused by other factors and moves the whole curve.

What are the determinants of demand?

Income, prices of related goods, tastes, expectations, population, and others, besides own price.

What are the determinants of supply?

Input prices, technology, taxes and subsidies, number of firms, weather, besides own price.