What Is a Computer and Its Parts
What is a Computer and a Computer System; Categories of Computers; The Computer System; Parts Inside the System Unit; Front of the System Unit
On this page8 sections
- 01Learning Objectives
- 02What is a Computer and a Computer System
- 03Categories of Computers
- 04The Computer System
- 05Parts Inside the System Unit
- 06Front of the System Unit
- 07Practical Work
- 08Scenario-Based Questions
Learning Objectives
- Name the parts of a computer and their functions.
- Identify the system unit, monitor and accessories.
- Locate the power supply, motherboard, processor, RAM and hard disk inside a system unit.
- State the function of each part.
What is a Computer and a Computer System
A computer is an electronic device that accepts data, processes it following instructions called a program, and produces useful output. Its main characteristics are speed, accuracy, storage ability, automation and versatility.
A computer system is not only the box on the desk. It has five parts that work together: hardware, the physical parts you can see and touch; software, the programs and instructions; peopleware, the people who use and maintain the system; data, the raw facts that are fed in; and infrastructure, the power supply, cables and environment.
Every task a computer performs follows the information processing cycle of input, processing, output and storage, which the parts of the system carry out together.
Categories of Computers
Computers can be grouped by size and power. A supercomputer is the largest and fastest, used for weather forecasting and scientific research. A mainframe handles many users at once, such as a bank processing millions of transactions. A minicomputer serves a small group, such as a university department. A personal computer is for one user and includes desktops, laptops and tablets.
Computers can also be grouped by purpose. A general purpose computer can do many different jobs, while a special purpose computer is built to do one job only, such as an automated teller machine.
The Computer System
A computer system is made of three main units. The system unit does the processing. The monitor shows the result. The accessories are the parts a user works with, such as the keyboard, mouse, printer and speakers. All three work together as one system.
The system unit is also called the CPU cabinet or the tower. It is the box that contains the parts that do the actual work. Everything a learner types goes into this box, and every result comes out of it.
Accessory means a part the user works with, such as a keyboard or printer.
Parts Inside the System Unit
The power supply unit converts mains electricity to the lower voltage the computer needs. The motherboard is the flat board that holds the parts and connects them. The processor, also called the CPU, does the calculating and controls the work.
RAM is temporary memory. It holds programs and data while the computer is working, and it is emptied when the power goes off. The hard disk is permanent storage. It holds the operating system, programs and files even when the computer is off.
Other parts include the drive bays for CD and DVD discs, the cooling fan that prevents overheating, and the expansion slots where extra cards can be added.
Front of the System Unit
The front panel carries the power button, the reset button, the power indicator light, headphone and microphone ports, and the optical drive. The back panel carries the power socket, the network cable port, and ports for the monitor, USB devices and speakers.
The monitor, formerly called the VDU, is the screen. Keyboard and mouse are the two devices a user cannot work without. Speakers produce sound. A printer gives a permanent copy called a hard copy.
| Category | Size and power | Example use |
|---|---|---|
| Supercomputer | Largest and fastest | Weather forecasting and research |
| Mainframe | Very powerful, many users | Bank transactions |
| Minicomputer | Mid sized, a small group | University department |
| Personal computer | One user | Desktop, laptop, tablet |
| Component | Function |
|---|---|
| Power supply unit | Converts mains electricity to the voltage the computer needs |
| Motherboard | Main board that holds and connects all parts |
| Processor (CPU) | Performs calculations and controls operations |
| RAM | Temporary memory used while the computer works |
| Hard disk | Permanent storage of the operating system, programs and files |
| Expansion slot | Slot for adding an extra card |
| Cooling fan | Removes heat to prevent damage |
| Monitor | Displays text, images and video |
| Keyboard and mouse | Used to type and to point, click and select |
| Printer | Produces a permanent paper copy |
| Speakers | Produce sound from the computer |
Practical Work
- Open a system unit cover with your teacher and locate the power supply, motherboard, processor, RAM and hard disk.
- Draw and label the system unit with at least ten parts.
- Touch and name each device on the workbench, then write its function in your notebook.
- Find the power button, reset button, power light and headphone port on the front of the tower.
Scenario-Based Questions
- A computer shows nothing on the screen when the power button is pressed. List three parts you would check first and explain why.
- Explain what would happen to a file saved in RAM when the computer is switched off.
- Your school wants to buy computers. State two reasons the processor and RAM matter more than the colour of the cabinet.
- Name four parts found inside a system unit and state one function each.
- A computer keeps restarting on its own. Which two parts could be responsible and how would you check?
- Explain the difference between a system unit and an accessory using two examples each.
- Draw the front panel of a system unit and label four features.
LEARNING OBJECTIVES: BY THE END OF THE LESSON PUPILS SHOULD BE ABLE TO:
| Cognitive | i. Name the parts of a computer and their functions. ii. Identify the system unit, monitor and accessories. iii. Locate the power supply, motherboard, processor, RAM and hard disk inside a system unit. iv. State the function of each part. |
| Affective | i. Appreciate the value of What is a Computer and Its Parts in school, at home and in the community. ii. Show willingness to use digital tools carefully, safely and responsibly. |
| Psychomotor | i. Open a system unit cover with your teacher and locate the power supply, motherboard, processor, RAM and hard disk. ii. Draw and label the system unit with at least ten parts. iii. Touch and name each device on the workbench, then write its function in your notebook. iv. Find the power button, reset button, power light and headphone port on the front of the tower. |
Rationale: A computer is an electronic device that accepts data, processes it following instructions called a program, and produces useful output. Understanding what is a Computer and a Computer System, categories of Computers, the Computer System, parts Inside the System Unit helps learners use digital technology confidently, safely and responsibly.
Pre-requisite Knowledge: In Week 2, learners studied History, Evolution and Generations of Computers, including what Evolution Means, early Counting and Calculating Devices, the Mechanical Era. The knowledge from that week is used again in this lesson.
Learning Material/Teaching Aid: Whiteboard, markers, computer or laptop where available, printed notes and charts on What is a Computer and Its Parts, practical task sheets, learners' notebooks and pens.
Reference Materials: Digital Technology for Junior Secondary Schools (JSS 1); NERDC Digital Technology Curriculum; Digital Technology JSS 1 First Term Notes (Week 3); First Term examination and Continuous Assessment question papers.
LESSON DEVELOPMENT
| Stage/Step (Time) | Teacher's Activities | Student's Activities | Learning Points |
|---|---|---|---|
| Introduction 5 MINUTES | Welcomes learners, revises Week 2 (History, Evolution and Generations of Computers) with two quick oral questions, and asks what they already know about What is a Computer and Its Parts. Elicits responses and writes the topic on the board. | Recall the previous lesson and share what they already know about What is a Computer and Its Parts. | Connecting prior knowledge to What is a Computer and Its Parts. |
| Step 1 6 MINUTES | Covers What is a Computer and a Computer System: A computer is an electronic device that accepts data, processes it following instructions called a program, and produces useful output. Its main characteristics are speed, accuracy, storage ability, automation and versatility. Covers Categories of Computers: Computers can be grouped by size and power. A supercomputer is the largest and fastest, used for weather forecasting and scientific research. | Listen, take notes and answer oral questions on "What is a Computer and a Computer System" and related points. | Understanding: What is a Computer and a Computer System; Categories of Computers. |
| Step 2 6 MINUTES | Covers The Computer System: A computer system is made of three main units. The system unit does the processing. The monitor shows the result. | Copy the key points, give examples from school and everyday life, and ask questions on "The Computer System". | Understanding: The Computer System. |
| Step 3 6 MINUTES | Covers Parts Inside the System Unit: The power supply unit converts mains electricity to the lower voltage the computer needs. The motherboard is the flat board that holds the parts and connects them. The processor, also called the CPU, does the calculating and controls the work. | Discuss in pairs, then report one point on "Parts Inside the System Unit" to the class. | Understanding: Parts Inside the System Unit. |
| Step 4 6 MINUTES | Covers Front of the System Unit: The front panel carries the power button, the reset button, the power indicator light, headphone and microphone ports, and the optical drive. The back panel carries the power socket, the network cable port, and ports for the monitor, USB devices and speakers. | Respond to questions, complete the examples on the board and note down "Front of the System Unit". | Understanding: Front of the System Unit. |
| Practical Work 6 MINUTES | Guides learners through the practical work: (i) Open a system unit cover with your teacher and locate the power supply, motherboard, processor, RAM and hard disk. (ii) Draw and label the system unit with at least ten parts. (iii) Touch and name each device on the workbench, then write its function in your notebook. Moves round the class to check progress and correct unsafe or careless use. | Carry out the practical tasks individually or in pairs and record what they did in their notebooks. | Applying the lesson through hands-on practice. |
| Evaluation 3 MINUTES | Asks learners to: i. Name the parts of a computer and their functions. ii. Identify the system unit, monitor and accessories. iii. Locate the power supply, motherboard, processor, RAM and hard disk inside a system unit. iv. State the function of each part. | Respond verbally and in writing to the evaluation questions. | Assessment and consolidation of the lesson content. |
| Conclusion 2 MINUTES | Recaps the main points: what is a Computer and a Computer System, categories of Computers, the Computer System, parts Inside the System Unit, front of the System Unit. Links them to the assignment and previews Week 4: Functions of Parts, Hardware and Software. | Listen, ask questions and copy the assignment. | Reinforcement of key concepts and a preview of the next lesson. |
Assignment: i. A computer shows nothing on the screen when the power button is pressed. List three parts you would check first and explain why. ii. Explain what would happen to a file saved in RAM when the computer is switched off.
On this page9 sections
- 01Lesson objectives
- 02Key vocabulary
- 03Common misconceptions
- 04Teacher activities
- 05Student activities
- 06Practical / learning evidence
- 07Resources and preparation
- 08Assessment for learning
- 09Inclusion and homework
Lesson objectives
By the end of the week, learners should be able to:
- Define a computer as a device that accepts data, processes it under stored instructions, stores it and produces output.
- State six characteristics of a computer, including speed, accuracy and lack of intelligence.
- Name the main parts of a computer system and give the function of each.
- Explain the roles of the ALU, control unit and registers inside the processor.
- Trace the input, process, output and storage cycle for one everyday task.
- Identify a computer system correctly from a mixed set of devices.
Key vocabulary
- Data: raw facts and figures with no meaning yet, such as a list of marks.
- Information: data that has been processed into a useful form, such as a learner's average score.
- CPU (processor): the part that carries out instructions.
- ALU: the arithmetic logic unit, which performs calculations and comparisons.
- Control unit: fetches instructions and directs the other parts in the correct order.
- Register: very fast temporary storage inside the processor.
- RAM: working memory that holds the programs and data in use. It loses its contents when power goes off.
- Motherboard: the main circuit board that connects the processor, memory and other components.
- Peripheral: a device connected to the system unit, such as a keyboard or printer.
Common misconceptions
- "The monitor is the computer." The monitor is an output device. The processing happens in the system unit.
- "The CPU and the system unit are the same thing." The system unit is the case. The CPU is one component inside it.
- "A computer is clever." A computer follows instructions exactly and has no understanding. Wrong input produces wrong output.
Teacher activities
- Starter: show a photograph of a full desktop setup and ask learners to circle the computer in the image. Collect and discuss the different answers.
- Define data, information and the input, process, output and storage cycle, using a familiar example such as computing a class average.
- Open a system unit if one is available (or use a labelled diagram) and name the motherboard, CPU, RAM, power supply, drive and cooling fan.
- Explain the CPU as the ALU, control unit and registers together, and model the fetch and execute idea with a simple routine: read the instruction, do it, store the result.
- Set a matching task: part cards to function cards, then ask pairs to justify two matches.
- Close with a "spot the computer system" set of images, including a phone, calculator, television and desktop.
Student activities
- Circle their answer on the starter image and explain their choice.
- Classify five given items as data or information.
- Label a blank system-unit diagram using the word bank.
- Write the function of six parts in one line each.
- Trace the cycle for an ATM withdrawal, naming the input, processing, output and storage at each step.
- Decide which images in the closing set are computer systems and give a reason.
Practical / learning evidence
A labelled diagram of a desktop computer system (at least eight labels with functions) and a completed four-column IPO table for two tasks: an ATM withdrawal and a school result calculation. Labels must be correct, legible and matched to the right part. A copied list of labels does not meet the criterion.
Resources and preparation
One working desktop or laptop, and if possible a non-working system unit that can be opened safely. Screwdriver, anti-static precautions, labelled diagram handout, word bank and part and function cards. Photographs of a phone, calculator, television and desktop. Offline route: printed diagram and cards. The real machine is optional. Never open a powered or plugged-in machine.
Assessment for learning
Check the diagram for correct placement and correct spelling. Ask three learners to explain one part without reading their notes. Mark the IPO tables for a sensible sequence. Learners who say the monitor is the computer need a concrete reteach using the opened unit.
Inclusion and homework
Give the word bank with the first letter of each part, and pair learners who struggle with writing at speed. Extend confident learners by asking what happens if RAM is too small for the program being opened. Homework: draw and label the computer setup you use at home or in the laboratory, and write one sentence on what each part does.