Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Computer Science
Lesson Topic: Describe the role and operation of interrupts
Learning Objective/s:
  • Describe what an interrupt is and why it is needed.
  • Identify hardware and software interrupts and give real‑world examples.
  • Explain the step‑by‑step sequence the CPU follows to service an interrupt.
  • Analyse how interrupt priorities and masking influence which ISR runs.
  • Apply knowledge by interpreting a flowchart of interrupt handling.
Materials Needed:
  • Projector or interactive whiteboard
  • Slide deck / printed handout on interrupts
  • Simple ISR simulation or code snippet (e.g., Python)
  • Worksheet with interrupt flowchart
  • Whiteboard and markers
  • Laptop for teacher demonstration
 Introduction:
Imagine typing a key and the screen updates instantly – that rapid response is thanks to interrupts. Review the concept of polling from the previous lesson, then state that today students will learn how interrupts let the CPU react without constant checking. Success will be measured by their ability to diagram and explain the interrupt service routine process.
Lesson Structure:
  1. Do‑now (5'): Quick written quiz contrasting polling vs. interrupt.
  2. Mini‑lecture (10'): Define interrupts, need, and types using slides.
  3. Demonstration (10'): Run a simple ISR simulation and walk through each handling step.
  4. Guided practice (15'): Students label a flowchart and answer worksheet questions on the interrupt sequence.
  5. Group activity (10'): Scenario on multiple interrupts – decide priorities and discuss masking.
  6. Check for understanding (5'): Exit ticket – one sentence describing the ISR sequence.
Conclusion:
Recap the key points: interrupts replace polling, each has a unique vector, the CPU saves context, and priorities ensure critical events are handled first. Collect exit tickets to gauge understanding, then assign a short homework task to create their own interrupt flow diagram for a chosen device.