JSS 1 First Term

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.

Practical Work

1. Open a system unit cover with your teacher and locate the power supply, motherboard, processor, RAM and hard disk.
2. Draw and label the system unit with at least ten parts.
3. Touch and name each device on the workbench, then write its function in your notebook.
4. Find the power button, reset button, power light and headphone port on the front of the tower.

Scenario-Based Questions

1. A computer shows nothing on the screen when the power button is pressed. List three parts you would check first and explain why.
2. Explain what would happen to a file saved in RAM when the computer is switched off.
3. Your school wants to buy computers. State two reasons the processor and RAM matter more than the colour of the cabinet.
4. Name four parts found inside a system unit and state one function each.
5. A computer keeps restarting on its own. Which two parts could be responsible and how would you check?
6. Explain the difference between a system unit and an accessory using two examples each.
7. 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:

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

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.