Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Computer Science
Lesson Topic: Show understanding of digital certification
Learning Objective/s:
  • Describe the purpose and components of a digital certificate and the surrounding PKI.
  • Explain the full lifecycle of a certificate from key‑pair generation to renewal or revocation.
  • Analyse how a web browser validates an HTTPS certificate, including chain‑of‑trust and revocation checks.
  • Compare CRL and OCSP revocation mechanisms and discuss their advantages and limitations.
  • Apply knowledge by interpreting the fields of a sample X.509 certificate.
Materials Needed:
  • Projector or interactive whiteboard for slides/diagrams
  • Printed handout of X.509 certificate fields and PKI components
  • Laptop with internet access for a live HTTPS validation demo
  • Sample digital certificates (PDF) for group analysis
  • Whiteboard and markers for sketching chain of trust
  • Optional QR‑code links to an online OCSP demonstration
 Introduction:
Begin with a quick poll: Who has seen the padlock icon in their browser? Review that the icon signals a secure connection and introduces digital certificates. State that today’s success criteria are to identify certificate components, trace its lifecycle, and demonstrate how browsers validate trust.
Lesson Structure:
  1. Do‑now (5') – Students answer the poll question and list what they think a digital certificate does.
  2. Mini‑lecture (10') – Present PKI, CA/RA roles, and key X.509 fields using slides.
  3. Guided activity (12') – In pairs, examine a sample certificate handout, label its fields, and map them to PKI components.
  4. Live demonstration (8') – Show an HTTPS handshake in a browser, display the certificate chain, and walk through validation and OCSP check.
  5. Comparison discussion (8') – Groups fill a quick chart comparing CRL vs. OCSP and share findings.
  6. Check for understanding (5') – Exit ticket: write one sentence explaining why the CA’s digital signature is essential.
  7. Homework briefing (2') – Assign the practice questions from the source material.
Conclusion:
Recap the main ideas: the role of a CA, the structure of an X.509 certificate, and the steps a browser takes to verify trust. Collect exit tickets to gauge individual understanding, and remind students to complete the practice questions for homework.