JSS 3 First Term

Learning Objectives

• Define a computer network and state why networks are used.
• Describe PAN, LAN, MAN and WAN by the area each covers.
• Explain how IP addresses and DNS help devices communicate.
• Apply rules of online safety and digital citizenship.

Starter Scenario

Three friends in the same classroom each have a document on their own phone. They want to share these documents with one another so that all three have all three documents. Two different ways they could share without using the internet include Bluetooth, sharing via a USB cable, a local Wi-Fi network, or passing the device round physically. Connecting devices together lets them share resources, and that is the heart of networking.

What is a Computer Network

A computer network is two or more computers or devices connected together so they can share resources such as files, printers, internet access and messages. Devices on a network are sometimes called nodes. Networks are set up for several reasons, including sharing files and folders, sharing hardware such as printers and scanners, sharing one internet connection, communicating through chat, email and video calls, and storing data centrally on a server. In a school setting, a network allows every student in the computer laboratory to use one printer, access shared folders on the server, and browse the internet through a single connection.

There are advantages to using a network. Resource sharing lets one printer be shared by many users, which saves money because the school does not need to buy a printer for every computer. Easy sharing of files between users means a teacher can place a document on a shared drive and every student can access it. Central storage means data can be stored on a server and accessed from any computer on the network. Fast communication allows users to message, email or video-call one another. Centralised security and backup protect data across all devices. A shared internet connection lets many users browse through one subscription.

There are also disadvantages and risks. If the network server breaks down, many users lose access at once. Networks can be attacked by hackers or viruses, creating a security risk. Equipment such as routers, switches, cables and servers is expensive to buy and maintain. Networks need skilled people to set up and manage them. Viruses can spread quickly from one device to another across the network.

Types of Networks

Networks are classified by the area they cover. A Personal Area Network, or PAN, is the smallest type, covering the space around one person. For example, when you connect a Bluetooth headset to your phone, you have created a PAN. A Local Area Network, or LAN, covers a limited area such as one building, school or office. A school computer laboratory where 30 computers share one printer and one internet connection is a typical LAN. A Metropolitan Area Network, or MAN, covers a city. For example, a university with campuses in different parts of Abuja might use a MAN to connect them. A Wide Area Network, or WAN, covers a very large area such as a country or the whole world. The internet itself is the largest WAN in existence.

The Internet and How it Works

The internet is a world-wide system of interconnected computer networks. It allows any device connected to it, whether computer, phone, tablet or smart TV, to send and receive information with any other connected device anywhere on Earth. Because it is a network of networks, the internet has no single owner. Many organisations and companies around the world help to keep it running. The internet supports many services, including the World Wide Web, email, messaging apps like WhatsApp and Telegram, video calls like Zoom and Google Meet, online games, streaming services like YouTube and Netflix, and cloud storage and online banking.

Many people confuse the internet with the World Wide Web, but they are different. The internet is the physical and logical network infrastructure that moves data. The World Wide Web is one service that runs on the internet, which lets us view web pages using a browser. An analogy is that the internet is like the network of roads and highways, while the World Wide Web is like the shops and buildings you visit along those roads. You need the roads, which represent the internet, to reach the shops, which represent websites.

When you visit a website, six steps happen in order. First, you type the address such as www.example.com into the browser. Second, the browser asks the DNS service to find the IP address of that server, like looking up a phone number in a directory. Third, your request is split into small pieces of data called packets. Fourth, the packets travel across many routers and networks until they reach the web server. Fifth, the server sends the web page back, also as packets. Sixth, your device reassembles the packets and displays the page. Every device has an IP address, like a home address, and the DNS works like a phonebook that matches website names to their addresses.

There are several means of accessing the internet. Fibre optics send data as light through thin glass cables at very high speed. Mobile broadband, including 3G, 4G and 5G, sends data via mobile phone networks using SIM cards and data plans from providers like MTN, Airtel, Glo and 9mobile. Satellite internet sends data to and from satellites in space, with providers like Starlink and VSAT. Wi-Fi lets a router broadcast internet into a local area wirelessly. Dial-up and DSL are older methods that use telephone lines.

Digital Citizenship and Online Safety

Digital citizenship means using technology responsibly, respectfully and safely. A good digital citizen respects other people online and uses polite language. A good digital citizen does not share other people's private information without permission and does not bully or harass others online. A good digital citizen respects copyright and does not steal other people's work. A good digital citizen uses strong passwords and keeps accounts secure. A good digital citizen thinks before posting, because what goes online stays online. A good digital citizen helps others stay safe.

Common online risks include phishing, which is a trick used to steal personal information by pretending to be a trusted person, such as a fake message saying you won a prize and asking you to click a link. Malware and viruses are harmful software designed to damage or steal data. Cyberbullying involves bullying using digital devices, such as sending mean messages to a classmate. Identity theft uses someone's personal details to impersonate them. Scams and fraud cheat people for money, such as fake online shops that never deliver. Inappropriate content includes harmful or unsuitable material. Stranger danger involves meeting or talking to strangers online who may not be who they claim to be.

To stay safe online, never share your passwords with anyone except your parents or guardian. Create strong passwords by mixing letters, numbers and symbols. Do not post your full name, address, phone number or school online. Do not accept friend requests or messages from strangers. Do not click suspicious links or open unknown attachments. Check before downloading apps or files and use official stores. Log out of shared computers and devices. Do not meet someone you met online in person without a trusted adult. Tell a parent or teacher immediately if something feels wrong online. Limit screen time and balance online time with offline activities.

Personal Online-Safety Plan

Every learner should draft a short personal plan with three parts. The first part is one rule you will follow for your password, such as never sharing it and changing it regularly. The second part is one type of personal information you will never share online, such as your home address or phone number. The third part is one action you will take if a stranger or scammer contacts you, such as blocking them and telling a trusted adult. This plan forms part of the JSS3 first-term project theme of using technology safely and responsibly.

Systems Diagnostic Activity

A school computer laboratory has 30 computers, one server and two printers. The lab wants all computers to share the printers, share files and access the internet, while keeping the students' accounts safe. The type of network best for this laboratory is a LAN. The device that should connect the lab to the outside internet is a router. The single resource that can be shared so only one printer is needed is the printer itself through hardware sharing. Central storage on a server is useful because files can be stored in one place and accessed by all. One online safety measure needed for the students' accounts is using strong passwords and not sharing them. If the server breaks, many users lose access at once, which is a disadvantage of networks.

Practical Work

1. List three ways two phones can share a file without using the internet.
2. Draw a table of the four network types and give one example of each.
3. State two advantages and two disadvantages of using a network.
4. Write a personal online-safety plan with three rules you will follow.

Scenario-Based Questions

1. A school in Abuja has 25 computers in one room and wants all of them to share a single printer. Should the school set up a PAN or a LAN? Explain your choice by comparing what each type covers.
2. Amina and Bola each have a document on their phones. They want to send the files to a third friend, Chidi, who is sitting right beside them. Which network type is best for this, and what technology would they most likely use?
3. Mr Odelami says the internet and the World Wide Web are not the same thing. A learner replies, But I use the internet to visit websites on the web. Write a short explanation that clarifies the difference.
4. A community centre installs fibre-optic internet but the cables are expensive. A nearby school on a tight budget wants internet access. Name two other ways to connect and say which one you would recommend for the school and why.
5. A new teacher opens a social media account and immediately posts the school address, her phone number, and a photo of the school compound. Identify two online safety mistakes the teacher made and explain how to fix each one.
6. A government office has 50 computers that all lost internet access at the same time. The ICT technician says the server is down. Explain why a single server failure can affect many users at once.
7. A pupil receives an email that looks like it is from his bank, asking him to click a link and enter his account number. Name the online trick being used and describe two steps the pupil should take before clicking.