Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Computer Science
Lesson Topic: Describe how a check digit is used and identify examples such as ISBN and bar codes
Learning Objective/s:
  • Describe the purpose of a check digit in data validation.
  • Explain how common check‑digit algorithms (e.g., ISBN‑10, ISBN‑13, EAN‑13) calculate the digit.
  • Apply the algorithm to compute or verify a check digit for sample identifiers.
  • Compare different weight patterns and moduli used in various schemes.
Materials Needed:
  • Projector or interactive whiteboard
  • Slide deck showing algorithms and examples
  • Printed worksheets with ISBN/EAN numbers
  • Barcode images or physical product labels
  • Calculator or spreadsheet software
  • Laptops with a simple programming environment (optional)
 Introduction:
Begin with a quick poll: how many students have scanned a book barcode or entered an ISBN? Explain that behind those numbers is a simple error‑detecting digit that helps ensure accuracy. Today we will uncover how check digits are generated and see real‑world examples such as ISBNs and retail bar codes. By the end, you will be able to calculate and verify check digits yourself.
Lesson Structure:
  1. Do‑Now (5'): Students write down any 13‑digit code they saw on a product and discuss its possible meaning.
  2. Mini‑lecture (10'): Define check digit, present the general formula, and illustrate weight patterns with slides.
  3. Guided practice – ISBN‑10 (10'): Walk through a step‑by‑step example; students complete the calculation on a worksheet.
  4. Guided practice – EAN‑13/UPC‑A (10'): Demonstrate the barcode calculation; students compute the check digit for a provided image.
  5. Pair activity (10'): Mixed identifiers are given; pairs calculate/check digits and identify any errors.
  6. Whole‑class debrief (5'): Review common mistakes and discuss why different schemes use different moduli.
  7. Exit ticket (5'): Write one sentence explaining why check digits are useful and give an example of a scheme.
Conclusion:
Summarize that check digits provide a low‑cost way to catch entry errors across many industries. For the exit ticket, each student stated a real‑world example and its benefit. Assign homework to create a short program or spreadsheet formula that validates an ISBN‑13. See you next lesson for deeper error‑detecting codes.