Functions of the CPU – Primary 3 Computer Studies Third Term Week 5
Functions of the CPU – Primary 3 Computer Studies Third Term Week 5
Class: Primary 3
Subject: Computer Studies
Term: Third Term
Week: 5
Topic: Functions of the CPU
Duration: 40 minutes
Theme: Computer Components
Keyword: CPU, Fetching, Decoding, Executing, Storing
Reference:
Lagos State Unified Scheme of Work
Basic Computer Studies Textbook for Primary 3
Behavioural Objectives
By the end of the lesson, pupils should be able to:
State the full meaning of CPU.
Describe the CPU as the brain of the computer.
Identify and explain the four basic functions of the CPU.
List the four steps of data processing in the CPU.
Set Induction (Entry Behaviour)
Teacher holds up a picture of a brain and asks:
“Who controls your thinking and actions? Just like the brain controls your body, the CPU controls the computer.”
Instructional Materials
Computer or motherboard with CPU visible (if possible)
Flashcards showing CPU functions
Chart with CPU process steps: Fetch → Decode → Execute → Store
CPU labelled diagram
Lesson Content
1. Meaning of CPU
CPU stands for Central Processing Unit.
It is the brain of the computer because it controls everything the computer does.
2. Functions of the CPU
The CPU performs four important steps when working with data:
a. Fetching
The CPU fetches instructions from the memory. Each instruction has an address. The program counter helps to locate these instructions.
b. Decoding
The CPU translates or decodes the instruction into a format (binary) it can understand. This is like reading the instruction carefully before doing anything.
c. Executing
The CPU carries out the instruction. It may:
Do calculations
Move data
Jump to another instruction
d. Storing
The CPU stores the result or sends it to the memory after finishing the task.
Teacher–Pupil Activities
| Teacher Activities | Pupil Activities |
|---|---|
| Explains the CPU as the brain of the computer | Listen and answer questions |
| Uses a diagram or computer to show where the CPU is | Observe and identify the CPU |
| Demonstrates each CPU step with real-life examples (e.g., cooking steps: gather, prepare, cook, serve) | Act out or repeat each CPU step |
| Guides pupils to recite the four functions of the CPU | Pupils repeat and write them down |
Class Activities
Activity 1: Pupils draw and label the CPU as the brain of the computer.
Activity 2: Pupils arrange flashcards with the four CPU steps in order.
Activity 3: Role-play CPU actions using “fetch,” “decode,” “execute,” and “store” as commands in a group game.
Evaluation Questions
What is the full meaning of CPU?
What part of the body is the CPU like?
List the four basic functions of the CPU.
What happens during the fetching stage?
What does the CPU do in the storing step?
Expected Answers:
Central Processing Unit
The brain
Fetching, Decoding, Executing, Storing
It takes the instruction from memory
It saves the result to memory
Conclusion
The CPU is very important in a computer. It works just like our brain by following steps to understand, process, and save instructions. The four major functions are: Fetching, Decoding, Executing, and Storing.
FAQs (Frequently Asked Questions)
Q1: Is the CPU inside or outside the computer?
Inside. It is a small part usually located on the motherboard.
Q2: Can a computer work without a CPU?
No. Without the CPU, the computer cannot process instructions.
Q3: What is the easiest way to remember CPU functions?
Use this trick: F-D-E-S → Fetch, Decode, Execute, Store.
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