Lesson Plan

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Lesson Plan
Grade: Date: 25/02/2026
Subject: Economics
Lesson Topic: Drawing and interpretation of average total cost (ATC) diagrams to illustrate economies and diseconomies of scale
Learning Objective/s:
  • Draw a complete ATC curve, label axes, and identify the Minimum Efficient Scale (MES).
  • Explain how the shape of the ATC curve reflects economies of scale (left of MES) and diseconomies of scale (right of MES).
  • Interpret the relationship between ATC, marginal cost (MC) and total cost (TC) in the context of firm decision‑making.
  • Analyse a given ATC diagram to determine the firm’s cost efficiency and strategic implications.
Materials Needed:
  • Projector and screen
  • Whiteboard and markers
  • Printed worksheets with blank graph paper
  • Calculator for each pair
  • Handout of a sample ATC diagram (including MC curve)
  • Sticky notes for exit tickets
 Introduction:
Begin with a quick poll: “What happens to a firm’s average cost when it grows larger?” Connect responses to prior knowledge of fixed vs. variable costs, then state that by the end of the lesson students will be able to draw and read an ATC diagram to spot economies and diseconomies of scale.
Lesson Structure:
  1. Do‑now (5'): Students list three factors that could lower a firm’s cost as output rises.
  2. Mini‑lecture (10'): Review ATC formula, introduce MES, and show a sample diagram.
  3. Guided drawing (15'): Teacher models plotting points and sketching the U‑shaped ATC curve on the board; students replicate on their worksheets.
  4. Pair activity (10'): Students add the MC curve, locate its intersection with ATC, and label economies/diseconomies of scale.
  5. Class discussion (10'): Groups share interpretations; teacher highlights key causes from the source table.
  6. Exit ticket (5'): On a sticky note, each student writes one real‑world example of an economy and one of a diseconomy of scale.
Conclusion:
Recap the ATC shape and its link to cost efficiency, confirming that the MC curve meets ATC at the MES. Collect exit tickets for immediate feedback, and assign homework: students must find a local business and sketch its estimated ATC curve, noting where economies or diseconomies might occur.