Lesson Plan

Resources → Subject Notes → Computer Science → Notes
Lesson Plan
Grade: Date: 25/02/2026
Subject: Computer Science
Lesson Topic: Show understanding of the purpose and roles of the Arithmetic and Logic Unit (ALU), Control Unit (CU) and system clock, Immediate Access Store (IAS)
Learning Objective/s:
  • Describe the functions of the ALU, CU, system clock, and IAS in a CPU.
  • Explain how the CU coordinates instruction fetch, decode, execution, and write‑back cycles.
  • Illustrate the data flow between the IAS registers and the ALU during an arithmetic operation.
  • Analyze the role of the system clock in synchronising CPU operations.
  • Apply knowledge by tracing a simple instruction through the CPU cycle.
Materials Needed:
  • Projector or interactive whiteboard for diagram display.
  • Printed handout of CPU component summary table.
  • Whiteboard and markers.
  • Student worksheets with instruction‑trace activities.
  • Laptop with CPU simulation software (optional).
 Introduction:
Begin with a quick question: “What part of a computer actually ‘does the thinking’?” Review students’ prior knowledge of basic computer components, then outline today’s success criteria: students will be able to name the key CPU components, describe their roles, and trace an instruction through the fetch‑decode‑execute cycle.
Lesson Structure:
  1. Do‑now (5'): Students complete a short quiz on CPU basics using a worksheet.
  2. Mini‑lecture (10'): Present the functions of the ALU, CU, system clock, and IAS with a block diagram.
  3. Guided demonstration (12'): Walk through the ADD R1,R2 example, highlighting each CPU stage.
  4. Pair activity (15'): Students trace a different instruction (e.g., SUB R3,R4) on a worksheet, identifying control signals and data paths.
  5. Whole‑class check (8'): Discuss pair results, use clicker questions to address misconceptions.
  6. Consolidation (5'): Exit ticket – write one sentence describing the role of the system clock in the CPU cycle.
Conclusion:
Recap the four main CPU components and their coordinated actions during an instruction cycle. Collect the exit tickets to gauge understanding, and assign a homework task: students must create a labelled diagram of the CPU showing the ALU, CU, system clock, and IAS, and annotate the data flow for an arithmetic operation.