JSS 2 First Term

Learning Objectives

• Name the hardware components of a network.
• Describe the common network topologies.
• Explain the parts of internet infrastructure.
• State rules for safe use of the internet.

Network Hardware Components

A network interface card, or NIC, is a part inside or attached to a computer that lets it join a network. It changes data from the computer into a form that can travel along cables, and changes incoming data back again.

A hub connects several computers but sends data to every computer connected to it, so it wastes traffic. A switch is smarter: it checks the destination and sends data only to the intended computer, so it is faster and is used in modern networks.

A router connects different networks, such as a school network and the internet. A modem converts digital data into signals that travel over telephone or cable lines, and back again. Network cables, such as Ethernet and fibre optic cables, carry the data, while a wireless access point sends data through radio waves for Wi-Fi.

Network Topologies

A topology is the layout of the computers and cables in a network. The choice of topology affects speed, reliability and cost.

In a bus topology all computers share one backbone cable. It is cheap but one break stops the whole network. In a star topology every computer connects to a central switch, so one broken cable affects only that computer, and it is the most common layout in modern schools and offices.

In a ring topology computers form a closed loop and data travels in one direction, but one break can stop the network. In a mesh topology every computer connects to every other, giving the greatest reliability but at a high cost. A hybrid topology mixes two layouts.

Internet Infrastructure

The internet is a global network of networks. It relies on several parts working together.

Servers are powerful computers that store websites, applications and data. Internet service providers, or ISPs, are companies that give users access to the internet, such as MTN, Glo, Airtel and Spectranet in Nigeria. Submarine cables are long fibre optic cables laid across the ocean floor that carry most traffic between continents. A data centre is a secure building that houses many servers.

Online Safety and Safe Surfing

Using the internet safely is an important skill. Strong passwords are the first line of defence against unauthorised access, and they should be long and private.

Learners should visit trusted websites, check that the address begins with https before entering personal details, and avoid clicking strange links or pop-ups. Personal information such as a full name, address and phone number should not be shared publicly. Suspicious messages should be reported to a trusted adult.

Digital Communication Tools

The internet provides many ways to communicate. Email sends messages and files across the world. Messaging apps send short messages, photos and documents. Voice and video calls let people speak and see each other over the internet. Social media lets users share posts, photos and videos with a wide audience.

Every online user should follow netiquette, which is the set of polite rules for communicating online. Good netiquette includes using a respectful tone and not sharing other people's private information.

Practical Work

1. Draw and label star, bus, ring and mesh topologies.
2. Locate the switch, router and cables in the school computer lab and state the job of each.
3. Write three safe surfing rules on a chart for the computer lab.
4. List three digital communication tools and state what each one is used for.

Scenario-Based Questions

1. A school lab has ten computers connected to one switch. What topology is this, and why is a switch better than a hub here?
2. A bank needs a network that keeps working even if one connection fails. Which topology is most suitable and why?
3. A school has a tight budget but needs a reliable network for thirty computers. Which topology would you recommend and why?
4. A company office connects each computer to a central device. If the central device fails, all lose connection. What topology and central device is this, and what is its main weakness?
5. A government agency needs the highest reliability. A technician suggests mesh. Explain why mesh is the best choice and give one disadvantage.
6. A small office has six computers and an employee suggests a bus topology to save cable cost. Give one advantage and one disadvantage of the suggestion.
7. Explain two rules for safe surfing that a learner should follow.

LEARNING OBJECTIVES: BY THE END OF THE LESSON PUPILS SHOULD BE ABLE TO:

Rationale: A network interface card, or NIC, is a part inside or attached to a computer that lets it join a network. Understanding network Hardware Components, network Topologies, internet Infrastructure, online Safety and Safe Surfing helps learners use digital technology confidently, safely and responsibly.

Pre-requisite Knowledge: In Week 4, learners studied Computer Networks, including what is a Computer Network, types of Networks, advantages of Networks. 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 Network Components and Topologies, practical task sheets, learners' notebooks and pens.

Reference Materials: Digital Technology for Junior Secondary Schools (JSS 2); NERDC Digital Technology Curriculum; Digital Technology JSS 2 First Term Notes (Week 5); First Term examination and Continuous Assessment question papers.

LESSON DEVELOPMENT

Assignment: i. A school lab has ten computers connected to one switch. What topology is this, and why is a switch better than a hub here? ii. A bank needs a network that keeps working even if one connection fails. Which topology is most suitable and why?