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Substitutes and Complements Network

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About This MicroSim

This MicroSim displays a network diagram of related goods showing both substitutes (green links) and complements (blue links) for a selected product. Students can choose from four products (Coffee, Smartphones, Movies, Pizza) and then simulate a price increase or decrease to observe how demand for related goods is affected. When the central product's price rises, substitute demand increases (consumers switch) while complement demand decreases (products bought together become less attractive), and vice versa.

How to Use

  1. Select a product from the dropdown menu (Coffee, Smartphones, Movies, or Pizza) to see its network of related goods displayed as connected nodes.
  2. Read the edge labels connecting the central product to surrounding nodes. Green edges indicate substitute goods and blue edges indicate complement goods.
  3. Click "Price Up" to simulate a price increase for the selected product. Watch the substitute nodes turn green (demand rises) and complement nodes turn red (demand falls), with animated size changes and labels showing the effect.
  4. Click "Price Down" to simulate a price decrease and observe the opposite effects on related goods.
  5. Click "Reset" to return to the neutral state, then try a different product to explore new sets of substitutes and complements.
  6. Read the explanation text at the bottom for a summary of why substitutes and complements respond differently to price changes.

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/related-goods-network/main.html"
        height="487px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Grade Level

9-12 (High School Economics)

Duration

10-15 minutes

Prerequisites

  • Understanding of the law of demand (price and quantity demanded move in opposite directions)
  • Awareness that consumers choose between different goods when making purchasing decisions

Activities

  1. Exploration (5 min): Select "Coffee" and click "Price Up." Identify which goods see increased demand (substitutes like Tea) and which see decreased demand (complements like Cream). Switch to "Pizza" and repeat. List at least three substitute-complement pairs.
  2. Guided Practice (5 min): Select "Smartphones" and click "Price Down." Explain to a partner why Phone Cases (a complement) would see increased demand when Smartphones become cheaper. Then discuss why Tablets (a substitute) would see decreased demand in the same scenario.
  3. Assessment (5 min): Choose any product and predict what will happen to each related good when the price changes before clicking the button. Write your predictions, then test them. For any incorrect predictions, explain why the actual result makes economic sense.

Assessment

  • Students can correctly classify goods as substitutes or complements based on how they relate to a given product
  • Students can predict how a price change for one good affects demand for its substitutes and complements
  • Students can explain the reasoning behind cross-price demand effects using real-world examples

References

  1. Substitute Good - Wikipedia - Explanation of substitute goods and cross-price elasticity of demand.
  2. Complementary Good - Wikipedia - Overview of complementary goods and how they move together in demand.
  3. Substitutes and Complements - Khan Academy - Lesson on factors that shift demand, including changes in the price of related goods.