Economics · Grade 9 · Markets and Price Determination · Term 1

Elasticity of Supply

Measuring the responsiveness of quantity supplied to changes in price.

• Ontario Curriculum Expectations
• CEE.Std3.9

About This Topic

Elasticity of supply measures the responsiveness of quantity supplied to a change in price. Grade 9 students calculate it as the percentage change in quantity supplied divided by the percentage change in price. Values greater than 1 indicate elastic supply, between 0 and 1 inelastic supply, and exactly 1 unit elastic supply. This concept fits within Ontario's economics curriculum on markets and price determination, where students use supply curves to visualize steep slopes for inelastic supply and flat slopes for elastic supply.

Key factors include spare production capacity, availability of inputs, time horizon, and mobility of resources. In the short run, supply tends to be inelastic due to fixed factors like plant size. In the long run, firms adjust by building new facilities or adopting technology, increasing elasticity. Students analyze how these affect producers' decisions, such as expanding output when prices rise.

Active learning suits this topic well. Students build intuition through graphing exercises, simulations of price shocks, and real-world cases from Canadian industries like oil sands or farming. These methods make abstract calculations concrete, encourage peer discussions on producer strategies, and strengthen graphing skills essential for economics.

Key Questions

1. Explain the factors that determine the price elasticity of supply.
2. Analyze how supply elasticity affects a producer's ability to respond to price changes.
3. Differentiate between short-run and long-run supply elasticity.

Learning Objectives

• Calculate the price elasticity of supply using given data for a specific product.
• Explain how changes in the availability of inputs affect the elasticity of supply for a manufactured good.
• Compare the short-run and long-run supply elasticity for a service industry, such as ride-sharing.
• Analyze how producers' decisions to increase output are influenced by the elasticity of supply in the agricultural sector.
• Differentiate between elastic and inelastic supply curves based on their slopes and the factors influencing them.

Before You Start

Introduction to Supply

Why: Students need to understand the basic concept of supply and the law of supply before they can analyze its responsiveness to price changes.

Calculating Percentage Change

Why: The calculation of price elasticity of supply relies on students' ability to accurately determine percentage changes in both price and quantity.

Graphing Linear Functions

Why: Interpreting the slope of supply curves is crucial for understanding elasticity visually, requiring familiarity with graphing concepts.

Key Vocabulary

Price Elasticity of Supply (PES)	A measure of how much the quantity supplied of a good or service responds to a change in its price. It is calculated as the percentage change in quantity supplied divided by the percentage change in price.
Elastic Supply	Occurs when the percentage change in quantity supplied is greater than the percentage change in price. The supply curve is relatively flat.
Inelastic Supply	Occurs when the percentage change in quantity supplied is less than the percentage change in price. The supply curve is relatively steep.
Unit Elastic Supply	Occurs when the percentage change in quantity supplied is exactly equal to the percentage change in price. The supply curve has a specific slope where the ratio is one.
Factors Affecting Supply Elasticity	These include the availability of inputs, spare production capacity, the time horizon considered, and the mobility of resources.

Watch Out for These Misconceptions

Common Misconception

Supply elasticity is the same as demand elasticity.

What to Teach Instead

Students often confuse the two, but supply focuses on producers' responses while demand covers consumers. Graphing both side-by-side in pairs clarifies differences. Active discussions reveal how elastic supply shifts curves rightward more readily.

Common Misconception

Supply is always elastic in the short run.

What to Teach Instead

Short-run supply is typically inelastic due to fixed capacity. Role-play scenarios where firms cannot quickly expand help students see constraints. Peer teaching reinforces long-run adjustments like new investments.

Common Misconception

Elasticity is constant along the entire supply curve.

What to Teach Instead

Elasticity varies by point on the curve; flatter sections are more elastic. Hands-on plotting activities let students measure changes at different points, correcting this through direct calculation and comparison.

Active Learning Ideas

Graphing Lab: Supply Elasticity Curves

Provide supply schedules for two goods. Pairs plot curves on graph paper, select price changes, calculate elasticity coefficients, and label sections as elastic or inelastic. Groups share one key insight with the class.

30 min·Pairs

Simulation Game: Price Shock Response

Assign small groups roles as producers of a good like lumber. Announce a price increase; groups list factors affecting their supply response and adjust quantity supplied on worksheets. Debrief differences in short-run versus long-run decisions.

40 min·Small Groups

Jigsaw: Elasticity Factors

Divide factors like time and inputs among small groups for expert research using handouts. Experts teach peers, then all apply factors to analyze elasticity for a Canadian product such as maple syrup. Complete summary charts.

35 min·Small Groups

Market Board Game: Elasticity Challenges

Whole class plays a board game where cards present price changes and scenarios. Teams roll dice to move, calculate elasticity, and decide production changes. Tally points for accurate responses.

45 min·Whole Class

Real-World Connections

• Farmers in southern Ontario must decide how much of their crop to bring to market when prices fluctuate. If they have storage capacity and can easily transport goods, their supply is more elastic, allowing them to respond to higher prices by selling more.
• The oil and gas industry in Alberta faces challenges in adjusting supply quickly to price changes. Building new extraction facilities or pipelines takes significant time and capital, making supply relatively inelastic in the short run.
• Manufacturers of popular electronics, like smartphones, may struggle to increase production rapidly when demand surges due to limited component availability and complex assembly lines. This can lead to an inelastic supply in the initial period after a price increase.

Assessment Ideas

Quick Check

Provide students with a scenario: 'The price of fresh strawberries increased by 10% due to a sudden heatwave. The quantity supplied increased by only 5%.' Ask students to calculate the PES and state whether the supply is elastic or inelastic, explaining their reasoning in one sentence.

Discussion Prompt

Pose the question: 'Imagine you are advising a small bakery and a large automobile manufacturer. How would the time it takes for each to increase production in response to a price change affect their supply elasticity? Discuss specific challenges each business might face.'

Exit Ticket

On an index card, have students draw two supply curves: one labeled 'Elastic Supply' and one labeled 'Inelastic Supply'. Below each curve, they should list one factor that contributes to that type of elasticity for a specific product (e.g., 'easy to find more flour' for elastic, 'limited factory space' for inelastic).

Frequently Asked Questions

What factors determine price elasticity of supply?

Factors include spare capacity, input availability, production time, and resource mobility. Producers with idle plants respond more elastically to price rises. Time matters most: short-run fixes limit changes, but long-run investments like new machinery boost responsiveness. Use Canadian examples, such as flexible auto parts versus rigid mining output, to illustrate in class.

How does short-run elasticity differ from long-run elasticity?

Short-run supply is inelastic because factors like factory size are fixed; producers adjust output along the curve. Long-run supply is more elastic as firms enter or exit, shift the curve. Teach with timelines: immediate crop response versus planting new fields. Graphs show steeper short-run curves flattening over time.

How can active learning help students understand elasticity of supply?

Active methods like supply curve graphing labs and price shock simulations make responsiveness tangible. Pairs calculate real coefficients from schedules, while group role-plays mimic producer decisions under constraints. These build graphing fluency, connect abstract math to markets, and spark debates on Canadian cases like oil production, deepening retention over lectures.

Why is supply elasticity important for producers?

It shows how well producers can adjust output to price changes, affecting revenue and profits. Elastic supply lets firms ramp up during booms; inelastic limits gains. Students analyze via scenarios: elastic tech firms versus inelastic farmers. This links to price determination and policy impacts in Ontario's economy.