Economics & Business · Year 11 · The Price Mechanism · Term 1

The Law of Demand

Examining the relationship between price and quantity demanded from a consumer perspective.

• ACARA Content Descriptions
• AC9EC11K03
• AC9EC11S03

About This Topic

The Law of Demand and Supply is the cornerstone of microeconomics, explaining how prices are determined in a competitive market. Year 11 students learn that, ceteris paribus, consumers will buy more of a product as its price falls, while producers will offer more as the price rises. This topic goes beyond simple price changes to investigate the non-price factors, such as consumer tastes, income, and production costs, that shift the entire demand or supply curve.

Mastering these concepts is essential for students to understand the price mechanism's role in resource allocation. It aligns with ACARA's requirements for students to use economic models to predict market outcomes. By applying these laws to current Australian markets, like the housing or energy sectors, students see the practical relevance of theory. This topic comes alive when students can physically model the patterns of market behavior through interactive trading games.

Key Questions

1. Explain the inverse relationship between price and quantity demanded.
2. Construct a demand curve from a given demand schedule.
3. Analyze the concept of diminishing marginal utility.

Learning Objectives

• Explain the inverse relationship between price and quantity demanded, citing the law of demand.
• Construct a demand curve graphically from a given demand schedule.
• Analyze the concept of diminishing marginal utility and its effect on consumer purchasing decisions.
• Calculate the price elasticity of demand for a product given changes in price and quantity demanded.

Before You Start

Introduction to Markets

Why: Students need a basic understanding of what a market is and the participants (buyers and sellers) involved before exploring specific market behaviors like demand.

Basic Economic Concepts

Why: Familiarity with terms like 'goods', 'services', 'price', and 'quantity' is essential for understanding the components of demand.

Key Vocabulary

Demand Schedule	A table that lists the quantity of a good or service that consumers are willing and able to purchase at various prices during a specific period.
Demand Curve	A graphical representation of the demand schedule, showing the inverse relationship between price and quantity demanded, with price on the vertical axis and quantity on the horizontal axis.
Diminishing Marginal Utility	The principle that as a consumer consumes more units of a good or service, the additional satisfaction (utility) gained from each extra unit decreases.
Quantity Demanded	The specific amount of a good or service that consumers are willing and able to buy at a particular price.

Watch Out for These Misconceptions

Common Misconception

A change in price causes a shift in the demand curve.

What to Teach Instead

A change in price only causes a movement along the curve (change in quantity demanded). Only non-price factors shift the entire curve. Using 'human graphs' where students move along a line helps reinforce this physical distinction.

Common Misconception

Supply and demand are the same thing.

What to Teach Instead

Demand represents consumer behavior, while supply represents producer behavior. They respond to price in opposite ways. Peer-to-peer role play where one student is the shopper and the other is the shopkeeper helps clarify these distinct perspectives.

Active Learning Ideas

Simulation Game: The Classroom Pit Market

Students are assigned roles as buyers and sellers of a simple commodity with secret 'limit prices.' They trade freely to find a market price, recording how their behavior changes as the teacher introduces 'shocks' like a new tax or a change in consumer preference.

60 min·Whole Class

Think-Pair-Share: The 'Why' Behind the Buy

Students list three things they bought recently and identify if a price change or a non-price factor, like a social media trend, influenced their decision. They then work with a partner to graph the resulting shift in demand.

20 min·Pairs

Stations Rotation: Shifting the Curve

Stations feature different news headlines, such as 'Floods hit Queensland sugar crops' or 'New study links coffee to longevity.' At each station, students must draw the resulting shift on a mini-whiteboard and explain the logic to their group.

40 min·Small Groups

Real-World Connections

• Retail buyers for companies like Myer or David Jones use demand schedules to predict how many units of a particular clothing item they should order at different price points to maximize sales.
• Economists at the Reserve Bank of Australia analyze demand curves for essential goods like housing and fuel to understand consumer behavior and inform monetary policy decisions.
• Event organizers for concerts or sporting matches adjust ticket prices based on demand curves, observing how many tickets are sold at various price levels to determine optimal pricing strategies.

Assessment Ideas

Quick Check

Provide students with a demand schedule for a popular smartphone. Ask them to plot the corresponding demand curve on graph paper and label the axes and the curve. Then, ask: 'What happens to the quantity demanded if the price drops by $50?'

Discussion Prompt

Pose the question: 'Imagine you are at a buffet. After eating your first plate of food, you feel very satisfied. How does the concept of diminishing marginal utility explain your desire for a second plate?' Facilitate a class discussion connecting this to purchasing decisions for other goods.

Exit Ticket

Students receive a scenario: 'The price of coffee increases from $4 to $5 per cup, and the quantity demanded falls from 100 cups to 80 cups per day.' Ask them to write one sentence explaining the relationship shown and identify whether this represents a movement along the demand curve or a shift of the curve.

Frequently Asked Questions

What is the difference between a movement and a shift?

A movement occurs along an existing curve when the price of the product itself changes. A shift happens when the entire curve moves left or right because of an external factor, like a change in consumer income or the cost of raw materials.

What does 'ceteris paribus' mean in Economics?

It is a Latin phrase meaning 'all other things being equal.' Economists use it to isolate the effect of one variable, like price, by assuming that everything else that could affect the market stays the same.

How can active learning help students understand supply and demand?

Active learning, particularly market simulations, allows students to experience the pressure of price changes. When a student 'seller' realizes they can't move their stock at a high price, the Law of Supply becomes a lived experience rather than just a line on a page.

How do seasonal factors affect supply in Australia?

Australia's climate significantly impacts agricultural supply. For example, a drought in the Murray-Darling Basin shifts the supply curve for fruit and vegetables to the left, leading to higher prices. Students can track these real-world shifts using supermarket price data.