Market Forces

Market Forces: market equilibrium, excess demand and excess supply for Edexcel IGCSE Economics

This free game is part of our Pearson Edexcel IGCSE Economics (4EC1) course for exams in EXAM YEARS 2027-2030.

Run the stalls at Oakfield market

Market Forces is a free 3D game about supply and demand for Pearson Edexcel International GCSE Economics (4EC1). It covers specification points 1.1.3 (g) to (j): equilibrium price and quantity and how they are determined, the use of diagrams to show how shifts in supply and demand affect equilibrium in real-world situations, how to define, calculate and draw excess demand and excess supply, and the use of market forces to remove them.

It’s Saturday at Oakfield market. You set the prices at three stalls: an apple stall, a pizza van and a honey stall. The queue in front of each stall is the quantity demanded and the crates on the counter are the quantity supplied, one person or crate for every 20 kg, 20 pizzas or 10 jars. Each crate goes to one buyer. Rosa, the market manager, explains each idea as you meet it, and a live demand and supply diagram and the stall’s table sit next to the market.

See excess demand and excess supply

• Excess demand: the apple stall opens at £1.00 per kg. Buyers want 500 kg but the farmer supplies only 100 kg, so 20 buyers stand at the back with nothing, waving cash. Excess demand = quantity demanded − quantity supplied = 400 kg, shown as a red gap on the diagram.
• Excess supply: the pizza van opens at £12. It has made 500 pizzas but buyers want only 100, so the unsold boxes pile up and glow. Excess supply = quantity supplied − quantity demanded = 400 pizzas.
• Market forces: press PRICE UP or PRICE DOWN, drag the price line on the diagram or tap the chalkboard. As the price rises, buyers walk away (demand contracts) and the farmer brings out more crates (supply extends). As it falls, more buyers join (demand extends) and stock goes back to the van (supply contracts). These are movements along the curves.
• Equilibrium: when every buyer has a crate and none are left over, the market clears. At £2.00 buyers want 300 kg and the farmer supplies 300 kg, so P1 = £2.00 and Q1 = 300 kg, the row in the table where the two columns match.

Shift the curves when the news breaks

Headlines from the Oakfield Gazette change the markets: an apple-a-day craze, cheese prices doubling, a poor summer for bees, half-price pears at the supermarket, a new turbo oven, a pay rise in town, a viral pizza advert and a rise in the price of bread. For each one you decide which curve shifts and which way, then grab the round D or S handle and drag it. The crowd changes at once: at the old price there is now excess demand or excess supply, so you clear the market again and read the new equilibrium, P2 and Q2. You see that when demand increases, price and quantity both rise; when supply decreases, price rises and quantity falls; and when demand and supply both increase by the same amount, quantity rises but the price stays the same.

Later rounds speed up. A trainee writes the wrong prices on all three boards at once, and in rush hour random headlines bring in more of the factors in the specification, such as indirect taxes, subsidies, population changes, falling incomes and the weather.

Learn it, then prove it

Everything is taught in the game before you’re tested on it. Three quick checks ask exam-style questions: calculate the excess demand at a price, find the equilibrium price and quantity from a table, and calculate the excess supply. A wrong move, such as cutting the price when there is already excess demand or shifting the wrong curve, brings up a short explanation with a “Why not?” and a link to the lesson, and then you try again. Leave a stall alone too long and market forces move the price themselves. The end screen gives your rank, your best score and a one-page summary for the exam.

The game takes about 7 to 10 minutes. It works with a mouse, a touch screen or the keyboard, needs no login and runs on school Chromebooks, so it’s easy to use as a starter or a plenary in an economics lesson.