Example · Economics and social sciences · Economics

An example of a course explained by Classy

Here’s what Classy produces from upper secondary school course material on the market: supply, demand and equilibrium. Everything is in the exact format the AI uses for a real course.

Open the interactive example Try with my course material

The course’s key ideas

The summary video starts with an overview.

A market is where buyers (demand) and sellers (supply) meet.
The more expensive a good is, the less people demand and the more sellers want to sell.
The equilibrium price is where the two curves intersect.
When something changes (weather, costs, trends…), a curve shifts and the price changes.

The outline: 3 topics

Classy breaks the course down in a logical order. Each topic has its own page, mini-video and quiz.

Demand
Why we buy less when prices are higher, and what can change what we want.
Pages 3 to 6 · about 10 minutes
Supply
Why sellers produce more when the price rises, and what changes when costs change.
Pages 7 to 10 · about 10 minutes
Equilibrium and shocks
Where the price settles, and why it moves when something changes.
Pages 11 to 16 · about 12 minutes

Topic 1: Demand

An extract from the topic page, exactly as the student sees it.

The key point

Demand is the quantity of a good that buyers want to buy at each price. The higher the price, the less people demand.

Q = 200 - 10P

The explanation

We’re not talking about a single quantity but a relationship: each possible price corresponds to a quantity demanded.

When we connect all these pairs (price, quantity) on a graph, we get the demand curve. It slopes downwards: this is the law of demand.

The intuition

Imagine croissants at the bakery. At 1 €, you buy two. At 2 €, just one. At 4 €, you give them a miss. Each price rise puts some buyers off. Add everyone together: the curve slopes downwards.

The analogy

The sales show demand in action: prices fall and suddenly the shops fill up. Nobody’s tastes have changed; only the price has moved.

Worked example: Demand for croissants

At 5 € per croissant, we substitute 5 for P:
$Q = 200 - 10 \times 5 = 150$
À 12 € :
$Q = 200 - 10 \times 12 = 80$
The price has risen by 7 €, so the quantity demanded has fallen by:
$150 - 80 = 70 \text{ croissants}$

Source: Pages 3 and 4 of the course material

Common pitfalls

Saying ‘demand falls’ when the price rises: it’s the quantity demanded that falls; the curve doesn’t move.
Forgetting that trends or income shift the curve.

Key takeaways

Demand = quantity wanted at each price
Price ↑ → quantity demanded ↓
Income, tastes, other prices → shift the curve

The quiz, with answers and explanations

Every wrong answer is explained: you learn from your mistakes too.

Cinema ticket prices rise from 8 € to 12 €. What happens?

A. The demand curve shifts to the left
B. We move along the curve: the quantity demanded falls (correct answer)
C. Demand increases because the cinema seems more prestigious
D. Nothing: demand does not depend on price

Why: It is the price of the good itself that changes: we move up along the curve, and the quantity demanded falls.

Exam-style exercise

The demand for concert tickets is $Q = 1000 - 20P$ . How many tickets are demanded at 30 €? At what price does demand fall to 0?

At 30 €, we substitute 30 for P:
$Q = 1000 - 20 \times 30 = 400 \text{ places}$
Demand falls to zero when:
$1000 - 20P = 0 \iff P = \frac{1000}{20} = 50$
Above 50 €, no one buys a ticket.

In the interactive example, you’ll also find the narrated video, the graph with a slider, topics 2 and 3, the mind map, the podcast, the revision sheet and the study plan. Open the full example →

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