Skip to content

Surplus Explorer

Run the Surplus Explorer MicroSim Fullscreen
Edit in the p5.js Editor

About This MicroSim

This MicroSim visualizes consumer surplus, producer surplus, and deadweight loss on a standard supply and demand graph. Students can adjust the market price away from equilibrium to see how total surplus shrinks and deadweight loss appears. The simulation calculates exact dollar values for each surplus area, making the abstract concept of economic efficiency concrete and measurable.

How to Use

  1. Adjust the Price slider to move the market price above or below the equilibrium price of $15.
  2. Observe the colored regions: blue represents consumer surplus (the benefit buyers receive above what they pay), orange represents producer surplus (the benefit sellers receive above their costs), and gray represents deadweight loss.
  3. Toggle the checkboxes to show or hide consumer surplus, producer surplus, and deadweight loss individually.
  4. Read the info panel on the right to see calculated dollar values for each surplus area and the total quantity traded.
  5. Click "Go to Equilibrium" to snap the price to the equilibrium point where total surplus is maximized.

Iframe Embed Code

You can add this MicroSim to any web page by adding this to your HTML:

<iframe src="https://dmccreary.github.io/economics-course/sims/surplus-explorer/main.html"
        height="532px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Grade Level

9-12 (High School Economics)

Duration

10-15 minutes

Prerequisites

  • Understanding of supply and demand curves
  • Knowledge of market equilibrium (where supply meets demand)

Activities

  1. Exploration (5 min): Start at equilibrium. Record the consumer surplus, producer surplus, and total surplus. Then move the price to $20 and record the same values. What happened to total surplus?
  2. Guided Practice (5 min): Move the price to $8 (below equilibrium) and then to $22 (above equilibrium). In both cases, compare the deadweight loss. Explain why any price other than equilibrium reduces total welfare.
  3. Assessment (5 min): A government is considering setting the price at $10. Using the simulation, calculate the deadweight loss this would create. Who loses more surplus -- consumers or producers? Explain your reasoning.

Assessment

  • Students can define consumer surplus and producer surplus and identify them on a graph
  • Students can explain why total surplus is maximized at the equilibrium price
  • Students can calculate and interpret deadweight loss when the market price deviates from equilibrium

References

  1. Economic surplus - Wikipedia - Overview of consumer surplus, producer surplus, and total surplus.
  2. Deadweight loss - Wikipedia - Explanation of how market inefficiencies create welfare losses.
  3. Consumer and Producer Surplus - Khan Academy - Video lessons on surplus concepts and graphical analysis.