Economics · Year 10 · The Economic Problem and Markets · Autumn Term

Price Elasticity of Demand (PED)

Measuring the responsiveness of quantity demanded to changes in price.

• National Curriculum Attainment Targets
• GCSE: Economics - Demand and Supply

About This Topic

Price Elasticity of Demand (PED) measures how quantity demanded responds to a price change. Students use the formula PED = (% change in quantity demanded) / (% change in price), taking the absolute value to focus on magnitude. They classify demand as price elastic (|PED| > 1, sensitive response), inelastic (|PED| < 1, less sensitive), or unitary elastic (|PED| = 1). Factors like substitute availability, necessity, income proportion spent, and time influence elasticity.

In the GCSE Economics curriculum's Demand and Supply theme, this builds skills for the 'Economic Problem and Markets' unit. Students calculate PED for products like coffee or fuel, then evaluate business pricing: raise prices on inelastic goods like medicines to boost revenue, lower on elastic luxuries like cinema tickets to increase sales volume. This fosters critical analysis of market strategies.

Active learning suits PED perfectly through simulations and data tasks. When students role-play price hikes in group markets or analyze real sales data collaboratively, formulas connect to business decisions. These methods make abstract concepts practical, improve calculation accuracy, and encourage evaluation of elasticity factors.

Key Questions

1. Calculate the price elasticity of demand for various products.
2. Evaluate why businesses consider PED when setting prices.
3. Explain how the availability of substitutes affects a product's elasticity.

Learning Objectives

• Calculate the price elasticity of demand for a given product using percentage changes in quantity demanded and price.
• Classify demand as elastic, inelastic, or unitary elastic based on calculated PED values.
• Analyze the impact of factors such as availability of substitutes and necessity on the price elasticity of demand for various goods.
• Evaluate how businesses use PED information to make strategic pricing decisions to maximize revenue.
• Explain the relationship between PED and a firm's total revenue.

Before You Start

Introduction to Demand

Why: Students need to understand the basic law of demand and the concept of quantity demanded before they can measure its responsiveness to price changes.

Calculating Percentage Change

Why: The formula for PED relies on calculating percentage changes, a fundamental mathematical skill.

Key Vocabulary

Price Elasticity of Demand (PED)	A measure of how much the quantity demanded of a good responds to a change in its price. It is calculated as the percentage change in quantity demanded divided by the percentage change in price.
Elastic Demand	Demand where the percentage change in quantity demanded is greater than the percentage change in price (|PED| > 1). Consumers are very responsive to price changes.
Inelastic Demand	Demand where the percentage change in quantity demanded is less than the percentage change in price (|PED| < 1). Consumers are not very responsive to price changes.
Unitary Elastic Demand	Demand where the percentage change in quantity demanded is exactly equal to the percentage change in price (|PED| = 1). Total revenue remains unchanged when price changes.
Substitutes	Goods or services that can be used in place of another. The availability of close substitutes generally makes demand more price elastic.

Watch Out for These Misconceptions

Common Misconception

PED is always positive since lower prices increase demand.

What to Teach Instead

PED is negative due to the inverse price-quantity relationship, but economists use the absolute value for magnitude. Graphing demand curves in pairs helps students see the downward slope and calculate correctly through hands-on plotting.

Common Misconception

PED stays constant for any product regardless of factors.

What to Teach Instead

Elasticity varies with substitutes, time, and necessity; insulin is inelastic short-term but more elastic long-term. Simulations introducing substitutes or time delays in groups reveal these shifts, correcting fixed views.

Common Misconception

Necessities always have inelastic demand.

What to Teach Instead

Strong substitutes can make necessities elastic, like branded vs generic painkillers. Role-play activities where groups test substitute impacts build understanding through observed demand changes and discussion.

Active Learning Ideas

Market Simulation: Price Hike Challenge

Divide class into firms selling goods with known PED values. Each firm announces a 10% price increase; student consumers vote to buy or switch using play money. Groups calculate resulting PED from demand shifts and discuss elasticity factors. Debrief as whole class.

45 min·Small Groups

Data Stations: PED Calculations

Set up stations with sales data for products like bread, smartphones, and petrol before/after price changes. Pairs calculate PED, plot demand curves on graphs, and classify elasticity. Rotate stations twice, then share findings.

35 min·Pairs

Substitute Debate Relay

Teams line up; first student draws a product and price change, calculates PED without substitutes. Next adds a substitute and recalculates. Relay continues with time factor. Fastest accurate team wins.

30 min·Small Groups

Business Strategy Role-Play

Assign roles as managers for elastic/inelastic products. In small groups, propose price changes based on PED, predict revenue, and present to class for peer vote on viability. Use provided elasticity data.

40 min·Small Groups

Real-World Connections

• Airlines constantly adjust ticket prices based on PED. For leisure travelers, demand is often elastic, so they might offer discounts during off-peak times. For business travelers, demand is more inelastic, allowing for higher prices.
• Pharmaceutical companies consider PED when pricing essential medicines. Because demand for life-saving drugs is highly inelastic, price increases can significantly boost revenue, though this is often subject to government regulation.
• Supermarket chains analyze PED for different product categories. They might run promotions on elastic goods like branded cereals to attract customers, while maintaining stable prices on inelastic staples like milk.

Assessment Ideas

Quick Check

Present students with two scenarios: Scenario A: A 10% price increase leads to a 20% decrease in quantity demanded. Scenario B: A 10% price increase leads to a 5% decrease in quantity demanded. Ask students to calculate the PED for each and classify the demand as elastic or inelastic.

Discussion Prompt

Pose the question: 'If a government wants to reduce smoking, should they increase taxes on cigarettes? Why or why not, considering the price elasticity of demand for cigarettes?' Facilitate a class discussion where students use PED concepts to justify their answers.

Exit Ticket

Give each student a product (e.g., smartphone, gasoline, concert tickets, tap water). Ask them to write: 1. Whether they believe demand for this product is elastic or inelastic. 2. One reason for their classification, referencing factors like substitutes or necessity. 3. How a business selling this product might use this information when setting prices.

Frequently Asked Questions

How do you calculate price elasticity of demand?

Use PED = |(%Δ quantity demanded) / (%Δ price)|. For example, if price rises 10% and quantity falls 20%, PED = |(-20)/10| = 2 (elastic). Practice with midpoint formula for accuracy between two points. Students master this via data stations, graphing results to visualize responsiveness.

Why do businesses need to know PED when setting prices?

PED guides revenue maximization: raise prices on inelastic goods (little sales loss, higher total revenue) and lower on elastic ones (more sales volume offsets price cut). Evaluate via case studies like tobacco (inelastic) vs streaming services (elastic). This links to GCSE exam scenarios on pricing strategies.

How does availability of substitutes affect PED?

More substitutes make demand elastic; consumers switch easily, like Coke vs Pepsi. Few substitutes, like electricity, yield inelastic demand. Time matters too: short-term inelastic, long-term elastic as alternatives emerge. Role-plays demonstrate by removing/adding substitutes and recalculating PED.

How can active learning help students grasp PED?

Simulations like mock markets let students experience demand shifts from price changes firsthand, making the formula tangible. Group data analysis of real products reinforces calculations and factors like substitutes. Debates on business decisions build evaluation skills. These cut misconceptions by 30-40% versus lectures, per studies, and boost GCSE application scores.