Simultaneous Demand and Supply Shifts Worksheet with Answers

This simultaneous demand and supply shifts worksheet asks students to distinguish a definite prediction from an outcome that depends on shift sizes. Students classify four events, calculate three market outcomes, and explain why an unchanged price does not mean nothing happened. Copy the student section into a handout; the teacher key appears below. The interactive graph below is for exploration; use the written data, not its default values, for the worksheet answers.

See it move

Make it move

Supply and demand at equilibrium, drawn by the interactive graph. Tap it to drag the curves, open the full version, or put it on your own site free, or turn it into a five-minute class activity.

Teacher setup

Allow about 25 minutes: five for the scenario table, ten for calculations, five for graph comparisons, and five for the exit check. These are suggested classroom timings. Students need a pencil and optional calculator. Begin after single-curve shifts are familiar. The worksheet is original practice, not a released examination question.

Use the competitive market model with downward-sloping demand and upward-sloping supply. Hold unstated influences constant, assume both stated changes occur, and compare the final equilibrium with the original equilibrium. If students need a single-shift refresher, start with the demand versus quantity demanded worksheet.

Student worksheet

A. Make only the prediction the evidence supports

For each separate market, identify both curve shifts. Predict equilibrium price and quantity as higher, lower, or indeterminate without shift sizes. Explain which two effects reinforce each other and which compete.

Does indeterminate mean that the variable must remain unchanged? Write a sentence explaining your answer.

B. Test three outcomes with numbers

An invented market has original demand Qd = 120 - 10P and supply Qs = 20 + 10P. P is dollars per item; Q is items per day. First calculate the original equilibrium. Then solve each independent case below. Each starts from the original market, not from the previous row.

1. Set quantity demanded equal to quantity supplied and solve for P in each case. Substitute back into both equations to check Q.

2. State the horizontal shift in each curve at any unchanged price.

3. Compare each new price and quantity with the original. Which result is shared by all three cases?

4. Sketch the original curves and one pair of new curves. Label axes, curves, and both equilibrium points. Use coordinates written as (quantity, price).

C. Exit check

A student says, 'Demand and supply increased, so they cancel and price stays the same.' Use two numerical cases from part B to correct the claim. Then explain whether a single unscaled sketch can establish the size of either shift in a real market.

Teacher answer key

Scenario 1: Demand shifts right and supply shifts right. Quantity rises; price is indeterminate. Scenario 2: Demand shifts right and supply shifts left. Price rises; quantity is indeterminate. Scenario 3: Demand shifts left and supply shifts right. Price falls; quantity is indeterminate. Scenario 4: Demand and supply both shift left. Quantity falls; price is indeterminate. In each ambiguous result, the separate changes exert opposing effects. An indeterminate variable could rise, fall, or remain unchanged.

Original market: 120 - 10P = 20 + 10P gives 100 = 20P, so P = $5 and Q = 70 items per day. Both equations return 70.

Demand shifts right by 40 items at every price in all three cases. Supply shifts right by 20 in A, 40 in B, and 60 in C. With these particular parallel linear curves, equal horizontal shifts leave price unchanged. Do not generalize that arithmetic rule to differently shaped shifts without checking their equations.

Graph intersections are originally (70, 5), then (100, 6), (110, 5), or (120, 4). The quantity result agrees across all cases, while the price result changes. The exit claim fits B only; A and C disprove it as a general rule. An unscaled sketch illustrates a possibility, not measured shift sizes.

Follow-up

Ask students who guessed unchanged to draw two possible final crossings before calculating. For extra practice, use the shift-combination guide and supply and demand sandbox. Sandbox values are separate from this worksheet's equations.

Concept reference

The invented scenarios, equations, and questions are original. The method of combining separate shift predictions is checked against OpenStax, Changes in Equilibrium Price and Quantity.