SS 1 First Term

Lesson objectives

By the end of the week, learners should be able to:

1. Explain the central processing unit as ALU plus control unit plus registers.
2. Name the main parts of a desktop system unit.
3. Describe how a motherboard connects all components.
4. Identify expansion slots and state when an add-on is needed.
5. Build or label an exploded diagram of a system unit.

Key vocabulary

• CPU: the processor, often called the brain of the computer.
• ALU: the arithmetic logic unit performing calculations.
• Control unit: fetches instructions and directs execution.
• Register: fast temporary storage inside the processor.
• Motherboard: the main circuit board connecting components.
• Expansion slot: a slot on the motherboard for extra hardware.
• Add-on: extra hardware that extends functionality.
• Exploded diagram: a diagram showing components separated visually.

Common misconceptions

• "The fan is optional on a desktop." Active cooling is required to prevent overheating.
• "The CPU and the system unit are the same." The CPU is one component inside the system unit.
• "Expansion cards fit anywhere." Cards must physically match the motherboard slot type.

Teacher activities

1. Starter: open a system unit if one is available and remove the CPU, memory and fan.
2. Define the CPU as ALU plus control unit plus and describe each piece separately.
3. Name the motherboard, RAM, ROM and expansion slot parts one by one.
4. Explain how the motherboard links every component physically.
5. Set a card-sorting task: picture cards matched to part labels.
6. Close with the exit question about expansion slots.

Student activities

1. Handle the opened system unit and name each removable part.
2. Label a blank exploded diagram with the five main components.
3. Sort the picture cards to match each component to its label.
4. Explain why a new add-on must fit the motherboard slot.
5. Decide whether a given add-on belongs inside or outside the case.
6. Answer the exit question in one sentence about expansion slots.

Practical / learning evidence

A completed exploded diagram with five main components labelled, a card-matching chart and a three-item expansion-slot reasoning exercise. Hand in all three for marking.

Resources and preparation

An actual desktop system unit opened safely, printed part cards and blank diagrams. Screwdriver and anti-static precautions out of reach. Offline route: printed cards and diagrams. Never open a powered or plugged-in machine.

Assessment for learning

Check the diagram for at least five correct entries. Mark the card matching for correct pairs. Ask two learners to explain the CPU role without notes. Watch for "the monitor is the computer" and correct it using the opened unit.

Inclusion and homework

Provide a partially completed diagram for learners who need scaffolding. Allow written rather than verbal explanations. Extend confident learners with six components and a second diagram of a laptop layout. Homework: name three components found only in a laptop and state their role.