G7: Networks and Digital Communication

Networks and Digital Communication

By Soleha Majeed

3.1 Accessing Websites

Lesson Objectives

Students will be able to:

• Understand what a server is and how it works

• Explain how websites are accessed using the internet

• Identify the parts of a URL

• Understand IP addresses and their purpose

• Explain the role of DNS (Domain Name Server)

Real-life link: Using the internet to open Google, YouTube, or school websites.

Introduction to Networks

• A network is a group of computers connected together to share resources.

• Networks can be found in schools, homes, and businesses.

• Let's explore the basic components that make up a network.

Multiple Choice

What is the main purpose of learning about URLs and IP addresses?

• To design websites

• To understand how websites are accessed

• To repair computers

• To create games

What is a Server?

A server is a powerful computer connected to a network that:

1. Receives requests from other computers (clients)

2. Processes the request

3. Sends back the result or forwards it

What is a Server?

Example: When you open a website, your computer requests data from a web server.

Real-life example: A waiter (server) takes your order, processes it in the kitchen, and brings food back.

Multiple Choice

What is the main job of a server?

• Store games

• Receive and respond to requests

• Control printers

• Turn off computers

Multiple Choice

The web server, website and internet are all same.

• True
• False
• The web server and website are the same
• The internet is a type of web server

Websites and Servers

• Websites are collections of data files

• These files are stored on web servers

• We access websites using the internet

Websites and Servers

• Example: School website stored on a server and accessed by students from home.

Real-life example: Books stored in a library; students borrow them when needed.

Multiple Choice

Where are website files stored?

• On the keyboard

• On personal computers only

• On servers

• In browsers

Why Use a Web Server?

Web servers can handle multiple tasks, such as sending and receiving emails, storing web applications, and processing FTP requests. However, the primary use of a web server is to host websites, making them functional and interactive for users worldwide.

Web browsers- A web browser is a software application used to find, retrieve, and display information resources (websites, images, videos)

Let take an example of Library

​🖥️ Web Browser – The Student
A web browser (Chrome, Edge, Firefox) is like a student in a school library.


Library Example: The student goes to the library to look for information.

The student does not store all the books.
The student requests a book from the librarian.

Computer Meaning: The browser requests a website It displays the web pages It does not store the website permanently

Let take an example of Library

🌐 Website – The Book

A website is like a book in the school library.

Library Example:

• A book contains information (text, pictures).

• Different books have different topics.

• Students read books but don’t keep them permanently.

Computer Meaning:

• A website contains web pages

• Pages include text, images, videos

• Examples: school website, Google, YouTube

📘 Example:

• A science book = science website

• A story book = story website

Let take an example of Library

🗄️ Web Server – The Library Building

A web server is like the school library building.

Library Example:

• The library stores all books

• Librarian finds and gives the requested book

• Many students use the same library

Computer Meaning:

• A web server stores websites

• It receives requests from browsers

• Sends the required web page back

🏫 One library = many books
🖥️ One server = many websites

Let take an example of Library

What is a URL?

A URL (Uniform Resource Locator) is the address of a website.

Example: https://www.cambridgeinternational.org/about-us/

Used by browsers to locate web pages.

Multiple Choice

What does URL stand for?

• Uniform Resource Locator

• United Resource Line

• User Remote Location

• Universal Record Link

Parts of a URL

A URL has three main parts:

1. Protocol

2. Domain name

3. Path

Multiple Choice

How many main parts does a URL have?

• 1

• 2

• 3

• 4

What is a Protocol? - (Rules)

A network protocol is a set of rules or a common language that allows different devices (like computers, phones, servers) to talk to each other over a network, ensuring they understand the data being sent and received, much like how humans use a shared language to communicate. These rules define how to format, send, and process data, enabling seamless communication despite different hardware or software. 

Multiple Choice

What is a protocol - networking (in easy words)?

• A protocol is a software application for browsing the internet.
• A protocol is a set of rules for communication between computers in a network.

Multiple Choice

http://www.google.com is an example of a what?

• URL
• IP address
• Browser
• Application

Part 1: Protocol

• First part of URL

• Rules for communication

• Example: https

HTTPS means secure data transfer.

Real-life example: Speaking the same language to communicate.

​

​

Multiple Choice

Which part of the URL shows the communication rules?

• Path

• Domain

• Protocol

Multiple Choice

Google Chrome, Mozilla Firefox and Microsoft Edge are all examples of what?

• Search engines
• Websites
• Web Browsers
• Text editors

Multiple Choice

You need a web browser (Chrome, firefox etc) to type a URL?

• Yes, you need a web browser to type a URL.
• No, a URL can be typed without a browser.

Part 2: Domain Name

• Middle part of URL

• Name of the web server

• Easy to remember for humans

Real life example: remembering the Contact name instead of the phone number

​

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Multiple Choice

What is the domain name in this URL? https://www.google.com/search

• https

• google.com

• www

• /search

Part 3: Path

• Last part of URL

• Shows exact web page or file you're looking for.

Example: /about-us/

Real-life example: Specific room number in a building.

​

​

Multiple Choice

Which part of the URL shows the file or webpage name?

• Protocol

• Domain name

• Path

• DNS

What is an IP Address?

An IP address (Internet Protocol address):

• Is a unique number

• Identifies each device on a network

• Helps data reach the correct device

Example: 192.168.42.1

Real-life example: Home address helps mail reach the correct house

Multiple Choice

What does an IP address do?

• Stores data

• Identifies devices on a network

• Protects computers from viruses

• Opens websites

Relationship Between URL and IP Address

• Every URL has a matching IP address

• Computers use IP addresses

• Humans use URLs

Example: URL: www.cambridgeinternational.org IP: 192.149.119.103

Real-life example: Phone contact name and phone number.


A URL (like www.google.com) is a human-friendly web address, while an IP address (like 142.250.186.46) is the actual numerical location of the website's server

Relationship Between URL and IP Address

• URL (Uniform Resource Locator): What you type in the browser (e.g., https://www.example.com/page). It tells your browser what to find and where, including the protocol, domain, and path.

• IP Address (Internet Protocol Address): A unique numerical label (e.g., 192.0.2.1) that identifies a specific device (server) on the internet, acting as its physical location. 

Relationship Between URL and IP Address

• Example

  • URL: www.wikipedia.org

  • Equivalent IP Address (Example): 198.35.26.96 (Wikipedia's IP, may vary).

Multiple Choice

Which one is easier for humans to remember?

• URL

• IP Address

Multiple Choice

What is a domain name?

• programming language.

• computer hardware.

• software application.

• human-readable address for a website.

What is DNS?

• DNS (Domain Name Server):

  • Special server

  • Matches domain names to IP addresses

  • Stores huge database

https://www.youtube.com/shorts/K9YWlljNsNw

What is DNS?

• A DNS (Domain Name Server) is a special server that:

  • Stores a database of domain names

  • Matches each domain name to an IP address

  Example:

  • Domain name: cambridgeinternational.org

  • IP address: 192.149.119.103

Multiple Choice

What information is stored on a DNS?

• user passwords and personal data.

• email account settings and preferences.

• mappings of domain names to IP addresses

Why DNS is Needed?

• Computers communicate using numbers (IP addresses)

• Humans prefer easy names (URLs)

• DNS acts as a translator between the two

Real-life example: Asking for “Ali” instead of dialing his full number.

Multiple Choice

Why do we need DNS?

• to store user passwords securely.

• To enhance video streaming quality.

• To resolve domain names to IP addresses and facilitate easier navigation on the internet.

How DNS Works – Step 1

Step 1: You type a URL into a web browser.

Example: cambridgeinternational.org

The browser understands this is a domain name, not an IP address.

Real-life example: Writing a name on a paper before finding the number.

Multiple Choice

What is typed first when opening a website?

• IP address

• Domain name (URL)

How DNS Works – Step 2

Step 2:

• The browser sends the domain name to a DNS

DNS checks its database for a matching IP address.

Real-life example: Asking a phone directory for a contact number.

Multiple Choice

Which software sends the request to the DNS?

• Web server

• Web browser

How DNS Works – Step 3

Step 3:

• DNS searches its database

• Finds the matching IP address

• Sends it back to the browser

Example: 192.149.119.103

Real-life example: Directory giving you the correct phone number.

Multiple Choice

What does the DNS send back to the browser?

• Website data

• Protocol

• IP address

How DNS Works – Step 4

Step 4:

• Browser sends a request to the web server

• Web server sends back the website data

Flow: Browser → DNS → Browser → Web Server → Website

Real-life example: Calling a number and speaking to the person.

Multiple Choice

Which computer stores the website data?

• DNS

• Web server

Many DNS Servers

• There are many DNS servers worldwide

• If one DNS cannot find the domain name:

  • It asks another DNS

  • This continues until found

Real-life example: Asking multiple teachers for information.

Multiple Choice

What happens if the first DNS cannot find the domain name?

• Request goes to another DNS

• Request stops

• Website opens anyway

When a Website is Not Found

• If no DNS finds the domain name:

• Browser shows a 404 error

404 error: Website does not exist or cannot be found.

Real-life example: Wrong phone number message.

Multiple Choice

What does a 404 error mean?

• Website is secure

• Internet is slow

• Website not found

Why Website Security is Important

• Protects personal information

• Prevents data theft

• Keeps payment details safe

Real-life example: Locking your wallet.

Multiple Choice

Why should websites be secure?

• To load faster

• to protect user data

• To increase storage

Checking Website Security – Protocol

• Secure websites use https

• The s stands for secure

• Data is encrypted

HTTP vs HTTPS:

• HTTP: Not secure

• HTTPS: Secure

Real-life example: Writing in secret code.

​https://www.youtube.com/shorts/bJGNl0Sv1kw

​https://www.youtube.com/watch?v=w0QbnxKRD0w

Multiple Choice

Which protocol shows a secure website?

• http

• ftp

• https

• www

Encryption Explained Simply

• Encryption turns data into secret code

• Only the correct server can read it

• Uses a special key called a cipher

Real-life example: Lock and key system.

Multiple Choice

What is encryption?

• Deleting data

• Copying data

• . Scrambling data to keep it safe

• Sending data faster

Padlock Symbol

• Appears in the address bar

• Locked padlock = secure site

• Warning symbol = not secure

Real-life example: Lock on a door.

Multiple Choice

What does a locked padlock symbol mean?

• Website is slow

• Website is secure

• Website is blocked

• Website is offline

Digital Certificates

• Proof that a website is real and secure

• Checked automatically by the browser

• Can be viewed by clicking the padlock

Real-life example: ID card verification.

​https://www.youtube.com/watch?v=c61HJnVvzsI

Multiple Choice

What is the purpose of a digital certificate?

• Design websites

• Store passwords

• Prove website identity

• Speed up internet

Stay Safe Online

• Always check https

• Look for padlock

• Use trusted websites

• Never share personal data on insecure sites.

Multiple Choice

What should you do before entering personal details?

• Ignore security

• Check website security

• . Refresh page

• Close browser

Practical Activity – Browsers

• • Open a website in two browsers

  • Check protocol, padlock, certificate

  • Compare differences

Multiple Choice

Why use different browsers in this activity?

• To compare security display

• To change IP address

Lesson Summary

• DNS matches domain names to IP addresses

• Browser contacts DNS first

• Secure websites use https

• Padlock and certificates show security

What is a Network?

A network is a group of two or more devices (computers, phones, tablets, printers, etc.) that are connected together so they can share data, resources, and services.

Examples:

• School computers connected to a printer

• Internet (the largest network in the world)

• Wi-Fi at home connecting phones and laptops

Multiple Choice

Which of the following best defines a computer network?

• A single computer used for personal work

• A system where devices are connected to share data and resources

​Ways to Connect Devices on a Network

Devices can be connected in two main ways:

1. Wired connection (using cables)

2. Wireless connection (using radio waves)

Each method has its own advantages and uses.

Real-life example:

• Wired: Using a landline phone

• Wireless: Using a mobile phone

​Wired Connections (Cable)

​Wireless Connections

Radio waves

Multiple Choice

This symbol on a device represents

• Internet

• Bluetooth

• WiFi

• Ethernet

Multiple Choice

What are the two main ways to connect devices in a network?

• Wired and wireless

• Bluetooth and fiber optic

• Satellite and coaxial

• LAN and WAN

Wired Network (Ethernet)

A wired network uses Ethernet cables to connect devices.

Common devices used:

• Ethernet cables

• Network switch

• Router

• Desktop computers

• Printers

Ethernet cables

Multiple Choice

Which cable is commonly used in a wired network?

• Coaxial cable
• Fiber optic cable
• Ethernet cable
• USB cable

Advantages and Disadvantages of Wired Networks

Advantages:

• Faster speed

• More stable connection

• More secure

Disadvantages:

• Less flexible

• Requires cables

• Harder to move devices

Real-life example: Using a wired microphone vs a wireless one.

Multiple Choice

Which is an advantage of a wired network?

• Easy to move devices

• Uses radio waves

• Stable and fast connection

• No cables needed

Network Devices

How will you build up a wired network group?

Switch

• Connects multiple devices in the same network.

• Sends data directly to the device that needs it (efficient).

• Example: Office switch connecting computers & printers.

Hub

• Old device, similar to a switch.

• Sends data to all devices in the network (less secure, slower).

• Example: Early computer labs often used hubs.

Hub VS Switch (Analogy)

• Hub = announcing to the whole class

• Switch = whispering to the right student.

Multiple Choice

A switch is more efficient than a hub because it:

• Sends data to all devices

• Sends data only to the intended device

Multiple Choice

Why are hubs less secure than switches?

• They send data to all devices, not just the target one

• They store all files

​Label the following in your notebooks

Multiple Choice

Which connection uses radio waves to transfer data?

• USB cable

• Wi-Fi

• HDMI cable

Wireless Network (Wi‑Fi)

A wireless network connects devices using radio waves instead of cables.

Main devices used:

• Wireless Access Point (WAP)

• Router (with built-in WAP)

• Laptops, phones, tablets

Multiple Choice

What type of waves are used in Wi‑Fi networks?

• Sound waves
• Infrared waves
• Microwaves
• Radio waves

Radio Waves Explained Simply

Radio waves are a type of electromagnetic radiation.

• Travel through air

• Move in waves

• Have wavelength and frequency

Higher frequency = shorter wavelength

Real-life example: Ripples in water when you throw a stone.

Multiple Choice

What does frequency mean?

• Distance between waves

• Number of waves per second

• Speed of light

• Power of signal

Frequency and GHz

• Frequency is measured in Hertz (Hz)

• 1 Hz = 1 wave per second

• Wi‑Fi uses Gigahertz (GHz)

• 1 GHz = 1 billion cycles per second

Real-life example: Fast vs slow clapping.

Multiple Choice

What does GHz stand for?

• gigawatt
• gigahertz
• gigabyte
• gigaohm

Wireless Access Point (WAP)

• A WAP allows devices to connect wirelessly to a network.

  • Sends and receives radio signals

  • Usually built into a router

  Real-life example: A teacher speaking through a microphone to students.

​https://www.youtube.com/watch?v=UyHPCDDd_zQ&t=54s

Wireless Network Diagram (Wi‑Fi)

• A WAP allows devices to connect wirelessly to a network.

  • Sends and receives radio signals

  • Usually built into a router

  Real-life example: A teacher speaking through a microphone to students.

Multiple Choice

Which device sends Wi‑Fi signals?

• Smartphone or tablet
• Modem or network switch
• Router or wireless access point
• Desktop computer or laptop

Advantages and Disadvantages of Wireless Networks

• Advantages:

  • Easy to move devices

  • No cables needed

  • Good for mobile devices

  Disadvantages:

  • Slower than wired

  • Can be affected by distance and walls

  • Less secure

  Real-life example: Using Bluetooth headphones.

Multiple Choice

Which is a disadvantage of wireless networks?

• Easy movement

• Uses cables

• Can be affected by walls

• Needs Ethernet

Ethernet vs Wi‑Fi (Comparison)

Multiple Choice

Which network type offers more mobility?

• Ethernet

• Wired

• LAN only

• WIFI

Choosing a Network for an Office

• Wired network best for:

  • Desktop computers

  • Printers

  • Servers

  Wireless network best for:

  • Laptops

  • Phones

  • Tablets

  Most offices use BOTH.

Multiple Choice

Why do offices often use both wired and wireless networks?

• Offices prefer only wireless networks for easier setup.
• to balance stability and flexibility.

What Are Radio Waves?

Radio waves are a type of electromagnetic radiation.
They move up and down, similar to ripples on water when a stone is thrown into a pond.

Radio waves are used to send data without wires in technologies like:

• Wi-Fi

• Bluetooth

• Mobile (cellular) networks

Real-Life Example

When you send a message on WhatsApp using Wi-Fi, the data travels as radio waves through the air.

Multiple Choice

Radio waves are mainly used for:

• Sending data wirelessly

• Medical imaging
• Weather forecasting
• Printing documents

Parts of Radio Waves

• A cycle is one complete wave from the top of one wave to the next.

• Wavelength is the distance between the tops of two waves.

• It shows how long the wave is.

Multiple Choice

What is the distance between two wave peaks called?

• Frequency

• Cycle

• Wavelength

• Speed

Frequency of Radio Waves

• Frequency means how many cycles happen per second.

  • More cycles per second = higher frequency

  • Fewer cycles per second = lower frequency

  Frequency is measured in Hertz (Hz).

Frequency of Radio Waves

Real-Life Example

Fast music beats = high frequency
Slow drum beats = low frequency

Note:

• Linking frequency to speed

Multiple Choice

Frequency tells us:

• How many waves occur per second

• How strong a wave is

• How far a wave travels

• How much data is stored

Gigahertz (GHz)

• 1 Hertz (Hz) = 1 cycle per second

• 1 Gigahertz (GHz) = 1 billion cycles per second

Most wireless networks use GHz frequencies.

Real-Life Example

Wi-Fi routers work at 2.4 GHz or 5 GHz, sending billions of waves every second.

Multiple Choice

1 GHz means:

• 1 thousand cycles per second

• 1 million cycles per second

• 1 billion cycles per second

• 1 trillion cycles per second

Types of Wireless Technology

• There are three main types of wireless technology:

  1. Wi-Fi

  2. Bluetooth

  3. Cellular networks

  All of them use radio waves to send data.

  Real-Life Example

  • Wi-Fi: Home internet

  • Bluetooth: Wireless headphones

  • Cellular: Mobile data (4G/5G)

Multiple Choice

Which is NOT a wireless technology?

• Wi-Fi

• Bluetooth

• Cellular network

• Ethernet

What Is a Wi-Fi Network?

• A Wi-Fi network connects devices without cables using radio waves.

  Devices connect to a Wireless Access Point (WAP).

  Real-Life Example

  Your phone connects to home Wi-Fi through the router.

Multiple Choice

Wi-Fi uses ______ to transmit data.

• Light waves

• Sound waves

• Radio waves

• Heat waves

Open Ended

What is the difference between Wireless Access Point and router?

Multiple Choice

What is the main job of a router?

• Connect a network to the internet

• to store data for future use.

• to display web pages

Wireless Network Interface Card (WNIC)

To connect to Wi-Fi, a device must have a WNIC.
It allows the device to:

• Receive radio waves

• Send radio waves back to the WAP

Real-Life Example

Laptops and smartphones have built-in WNICs.

Multiple Choice

Which component allows a device to use Wi-Fi?

• CPU

• RAM

• Hard disk

• WNIC

Wi-Fi Range and Speed

• Average Wi-Fi range: 50 metres

• Maximum speed: up to 1300 Mbps

• Average speed: about 200 Mbps

Real-Life Example

Wi-Fi is stronger near the router and weaker far away.

Wi-Fi Range and Speed

• Check your wifi speed www.fast.com

Multiple Choice

Wi-Fi speed is measured in:

• bytes per second (Bps)
• terabytes per second (TBps)
• megabits per second (Mbps) or gigabits per second (Gbps)
• kilobytes per second (KBps)

2.4 GHz vs 5 GHz Wi-Fi

​Real-Life Example Use 5 GHz near router, 2.4 GHz in far rooms.

Multiple Choice

Which frequency is better through walls?

• 5 GHz

• 2.4 GHz

• Both

• Neither

What is Bluetooth Wireless Technology?

Bluetooth Wireless Technology is a type of wireless network that allows devices to connect to each other over short distances. It does not require a router or Wireless Access Point (WAP). Devices communicate directly using radio waves.

Bluetooth is commonly used to connect personal devices quickly and easily.

Real-Life Examples

• Connecting wireless headphones to a mobile phone

• Using a wireless mouse or keyboard with a computer

• Sending photos from one phone to another nearby phone

Multiple Choice

Bluetooth Wireless Technology is mainly used for:

• Long-distance internet access

• Short-distance device connections

• Website hosting

• Email communication

Devices Connected Using Bluetooth

Bluetooth is useful for connecting small personal devices. These devices communicate directly with each other without needing cables.

Bluetooth connections are usually one-to-one or one-to-few.

Real-Life Examples

• Phone ↔ Bluetooth speaker

• Laptop ↔ wireless keyboard

• Tablet ↔ stylus pen

Multiple Choice

Which of the following is best connected using Bluetooth?

• Desktop computer to printer across a building

• Smart TV to internet router

• Mobile phone to wireless earbuds

• School computers in a lab

What is Pairing?

Pairing is the process of connecting two Bluetooth devices for the first time. During pairing, the devices exchange information so they can recognise each other in the future.

Once paired, devices can reconnect automatically.

Real-Life Example

Pairing is like exchanging phone numbers with a friend. Once saved, you do not need to exchange numbers again.

Multiple Choice

What is the first-time connection between Bluetooth devices called?

• Linking

• Pairing

• Routing

• Sharing

Steps to Pair Bluetooth Devices

To pair Bluetooth devices:

1. Turn on Bluetooth on both devices

2. Devices scan for nearby Bluetooth devices

3. Select the device you want to connect

4. Enter a password or code if required

After this, the devices are paired.

Multiple Choice

Which step happens first when pairing Bluetooth devices?

• Enter a password

• Select the device

• Turn on Bluetooth

• Send data

Bluetooth Speed and Frequency

Bluetooth Wireless Technology:

• Transmits data at speeds of up to 25 Mbps

• Operates at a fixed frequency of 2.45 GHz

• Uses less power than Wi-Fi

Real-Life Example

Bluetooth uses less battery, which is why it is used in wireless earbuds.

Multiple Choice

Bluetooth operates at which frequency?

• 1.8 GHz
• 5.0 GHz
• 900 MHz
• 2.45 GHz

Bluetooth Hardware Requirements

To use Bluetooth, a device must have a Bluetooth transmitter built into it. If a device does not have Bluetooth, a Bluetooth adapter can be used.

Adapters usually connect through a USB port.

Real-Life Example

Using a USB Bluetooth adapter on an old desktop computer.

Bluetooth Adapter vs Transmitter

Bluetooth Transmitter

• Purpose: Converts wired audio into a wireless signal to send to headphones or speakers.

• Use Case: Plugging a 3.5mm jack into an airplane seat, old TV, or gym equipment to use wireless headphones.

• Direction: One-way (Output only). 

Bluetooth Adapter (USB/Dongle)

• Purpose: Adds native Bluetooth capability to a device, usually a PC or laptop that lacks it.

• Use Case: Plugging a USB dongle into a PC to connect Bluetooth mice, keyboards, or headphones.

• Direction: Two-way (Data transfer and audio). 

Multiple Choice

What can be used to add Bluetooth to a device that does not support it?

• Router

• Ethernet cable

• Bluetooth adapter

• Modem

Bluetooth Speed and Frequency

Bluetooth Wireless Technology:

• Transmits data at speeds of up to 25 Mbps

• Operates at a fixed frequency of 2.45 GHz

• Uses less power than Wi-Fi

Multiple Choice

Bluetooth operates at which frequency?

• 5 GHz

• 2.45 GHz

• 1 GHz

• 10 GHz

Bluetooth Range

Bluetooth is designed for short-range communication.

• Typical range: 10 metres

If devices move too far apart, the connection may stop.

Real-Life Example

Music stops playing when you walk too far away from your phone while wearing Bluetooth headphones.

Multiple Choice

What is the typical range of Bluetooth Wireless Technology?

• 100 metres

• 50 metres

• 10 metres

• 1 kilometre

Bluetooth Symbol

There is a global symbol that shows a device can use Bluetooth. This symbol is recognised worldwide.

Real-Life Example

The Bluetooth symbol on phones, laptops, and car dashboards.

History of Bluetooth

Bluetooth technology began in 1994. It was developed by Jaap Haartsen, a Dutch engineer.

It was originally a code name during development.

Real-Life Example

Bluetooth is older than smartphones but still widely used today.

Multiple Choice

Who helped develop Bluetooth technology?

• Jaap Haartsen and Sven Mattisson at Ericsson

• Bill Gates and Paul Allen at Microsoft
• Steve Jobs and Tim Cook at Apple
• Mark Zuckerberg and Sheryl Sandberg at Facebook

Why is it Called Bluetooth?

Bluetooth is named after King Harald Bluetooth, who united Denmark and Norway.

The logo comes from two ancient symbols representing his initials.

Real-Life Example

Just like the king united countries, Bluetooth connects devices.

Multiple Choice

Bluetooth was named after:

• A computer scientist

• A radio wave

• A king

• A company

Why is it Called Bluetooth?

The technology was going to be called "Radio Wire" but the company decided the name "Bluetooth"



Logo was based on two ancient symbols

Multiple Choice

What were the two ancient symbols that bluetooth logo is based on?

• The initials 'H' and 'B' in Nordic runes.
• The letters 'A' and 'C' in Greek alphabet.
• The symbols 'X' and 'Y' in Egyptian hieroglyphs.
• The characters 'M' and 'N' in Latin script.

What is a Cellular Network?

A cellular network is a type of wireless network that uses radio waves to transmit data over large geographical areas.

Unlike Wi-Fi and Bluetooth:

• Wi-Fi works only inside homes, schools, or offices

• Bluetooth works only for very short distances

• Cellular networks cover cities, towns, and even highways

Cellular Networks

​Cellular networks are divided into hexagonal shapes to divide geographic areas into service zones, allowing for efficient, gap-free coverage and maximum frequency reuse to minimize interference.

Cellular Networks

Key Reasons for Hexagonal Cell Division:

• Optimal Coverage: Hexagons provide the best approximation of a circle (the theoretical radiation pattern of an antenna) without leaving gaps or overlapping.

Multiple Choice

Which statement is true for Cellular networks?

• Cellular networks use circular shapes to maximize coverage and minimize costs.
• Cellular networks are divided into square shapes to simplify the design and enhance capacity.
• Cellular networks are arranged in triangular shapes to improve data transmission and reduce latency.
• Cellular networks are divided into hexagonal shapes to cover areas efficiently and reduce signal interference.

What is a Cellular Network?

Mobile phones use cellular networks so people can:

• Make calls

• Send messages

• Use mobile internet
  even while moving from place to place.

Real-Life Example

When you travel from your home to school and still use mobile data, your phone stays connected because of a cellular network.

Multiple Choice

Which feature best describes a cellular network?

• Works only inside buildings

• Has very small range

• Covers large geographical areas

• Uses cables for data transfer

Compare these!

Emphasize range comparison (Bluetooth → Wi-Fi → Cellular)

​VS

Why Is It Called a “Cellular” Network?

The large area covered by a cellular network is divided into smaller regions called cells.

Each cell:

• Covers a small area

• Has its own base station

• Communicates with mobile phones using radio waves

Why Is It Called a “Cellular” Network?

This structure helps:

• Reduce congestion (blocking or overcrowding)

• Maintain strong signal quality

• Support millions of users

Real-Life Example

A city is divided into different neighborhoods. Each neighborhood has its own mobile tower serving nearby users.

Multiple Choice

What is a “cell” in a cellular network?

• A mobile phone

• A SIM card

• A small geographical area

• A satellite

What Is a Base Station? (Central communication hub)

A base station is a common term used in telecommunications for a radio receiver with one or more antennae.


While the base station has many other applications, it’s often used for mobile telephony, wireless communications, and even wireless computer networking. 

What Is a Base Station? (Central communication hub)

A base station is a fixed structure that:

• Sends and receives radio signals

• Connects mobile phones to the network

• Communicates with other base stations

Each cell has one base station, usually located on:

• Towers

• Rooftops

• High buildings

Real-Life Example

Those tall mobile towers you see near roads or buildings are base stations..

Multiple Choice

What is the main job of a base station?

• To manage power distribution for mobile devices.
• To store data for mobile applications.
• To provide internet access to stationary devices.
• To facilitate communication between mobile devices and the network.

How a Mobile Phone Call Works

When you make a call using your mobile phone:

1. Your phone sends radio signals to the nearest base station

2. The base station finds the cell of the receiver

3. Signals travel from base station to base station

4. The signal reaches the correct phone

This process happens in seconds.

Real-Life Example

Calling a friend in another city — your voice travels through many base stations before reaching them.

Multiple Choice

What happens first when you make a phone call?

• Signal goes directly to the other phone

• Signal goes to the nearest base station

• Signal goes to a satellite

• Signal is stored on the phone

Moving Between Cells (Handover)

When you move:

• Your phone leaves one cell

• Enters another cell

• Automatically connects to a new base station

This process is called handover.

Sometimes, during handover:

• The call may drop briefly

• Internet may pause for a second

Real-Life Example

While travelling in a car, your call disconnects for a moment and then reconnects.

Multiple Choice

Why might a call drop briefly while travelling?

• Phone battery is low

• A call might drop when the phone is in airplane mode unintentionally.
• Phone is damaged

• Phone is switching base stations
  

Generations of Cellular Networks

Cellular networks have evolved over time. These versions are called generations.

Main generations:

• 3G – Older, slower

• 4G – Faster, supports video streaming

• 5G – Very fast, low delay

Each new generation improves:

• Speed

• Capacity

• Performance

Real-Life Example

Older phones struggle with video calls, while newer phones stream smoothly.

Why Is 5G Better Than 4G?

https://www.youtube.com/watch?v=bGxhPG3H5BQ&t=104s

Multiple Choice

What does “G” stand for in 4G and 5G?

• Group
• Gigabyte

• Grade
• Global

Comparing 3G, 4G, and 5G

Comparing 3G, 4G, and 5G

Why Is 5G Better Than 4G?

5G is better because:

• Much higher speed

• Lower latency (less delay)

• Can connect many devices at once

• More reliable connections

It supports:

• Smart cities

• Self-driving cars

• Online gaming

• Remote surgery

Real-Life Example

Smart traffic lights using 5G can change signals instantly to avoid traffic jams.

Multiple Choice

Which is an advantage of 5G?

• Slower internet

• Higher delay

• Works only indoors

• Supports many devices

3.3: Data Transmission

What Is a Cipher?

A cipher is a method used to encrypt (scramble) data so that other people cannot understand it.

When we encrypt data:

• The original message is called plaintext

• The scrambled message is called ciphertext

• The method used to scramble it is called a cipher

What Is a Cipher?

Encryption helps protect:

• Passwords

• Bank details

• Personal messages

• Photos

Real-Life Example

When you send a message on WhatsApp, it is encrypted. If someone intercepts it, they cannot read it because it is scrambled.

Multiple Choice

What is the main purpose of a cipher?

• To delete data

• To scramble data for security

• To increase internet speed

• To store files

Creating Your Own Cipher (Example)

Let’s create a simple cipher.

Step 1: Choose Method

We will use letters.

Creating Your Own Cipher (Example)

Step 2: Rule

Each letter moves forward 2 letters in the alphabet.

A → C
B → D
C → E

Step 3: Encrypt Message

Message:
HELLO FRIEND

Encrypted:
JGNNQ HTKGPF

Real-Life Understanding

This is similar to the Julius Caesar cipher, where letters were shifted in the alphabet.

Multiple Choice

If the rule is “shift 1 forward”, what is CAT?

• DBU

• BZS

• CAU

• CBT

What Is an Error in Data?

An error in data is when information becomes incorrect due to a mistake or accidental change.

Errors can happen when data is:

• Created

• Processed

• Stored

• Accessed

• Transmitted

This is called data corruption.

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Real-Life Example

If you send money online and the amount changes from $50 to $500 due to a system error — that is data corruption..

Multiple Choice

Data corruption means:

• Data is improved

• Data is copied

• Data becomes incorrect

• Data is encrypted

Binary and Computers

Computers only understand binary.

Binary uses only:
0 and 1

Example:
55 in binary = 110111

Each 0 or 1 is called a bit.

All:

• Text

• Pictures

• Videos

• Music

are stored as binary.

Binary and Computers

Real-Life Example

When you save a photo, it is actually stored as millions of 0s and 1s.

​https://www.youtube.com/watch?v=PPiDK2YA9RE

Multiple Choice

Binary uses how many digits?

• 4
• 8
• 3
• 2

Example of Transmission Error

Original binary:
110111 (55)

After transmission error:
110011 (51)

Where is the error?

Example of Transmission Error

Original binary:
110111 (55)

After transmission error:
110011 (51)

One bit changed from 1 → 0

That small change altered the number completely.

Example of Transmission Error

Real-Life Example

Imagine sending exam marks electronically and one digit changes accidentally.



82/100 → 62/100

Multiple Choice

If one bit changes during transmission, what can happen?

• Nothing changes

• The data may become incorrect

• The data becomes faster

• The data becomes encrypted

Data Loss During Transmission

Sometimes data is not changed — it is lost.

Example:
Original: 11011110111
Received: 10111

Missing bits cause wrong value.

This leads to incomplete or corrupted data.

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Real-Life Example

A downloaded video stops halfway due to data loss.

Multiple Choice

If some bits are missing during transmission, this causes:

• Faster internet

• Encryption

• Perfect data

• Data loss error

Electricity Surges

When data travels through cables, it is sent using electric signals.

An electricity surge is a sudden increase in voltage in the electrical supply.

This surge can:

• Disrupt data transmission

• Change bits (0s and 1s)

• Cause data loss

• Damage hardware

Because computers use binary (0s and 1s), even a small voltage change can alter the data.

Electricity Surges

Real-Life Example

During a thunderstorm, lightning causes a power surge.
Your computer suddenly shuts down while saving a file.
When you reopen it, the file is corrupted.

Multiple Choice

What is an electricity surge?

• A slow decrease in voltage

• A wireless signal

• A type of encryption

• A sudden increase in voltage

Multiple Choice

An electricity surge can cause:

• More storage

• Data errors

• Encryption

• Faster internet

Voltage Surge Protectors

A voltage surge protector (or SPD) safeguards sensitive electronics from dangerous, temporary increases in voltage caused by lightning, grid switching, or large appliance startup

Radio-Wave Interference

Wireless devices (Wi-Fi, Bluetooth, cellular networks) use radio waves.

In crowded areas:

• Many devices send signals at the same time.

• Radio waves can mix together.

• Signals may become unclear or corrupted.

This mixing of radio waves is called interference.

Radio-Wave Interference

Interference can:

• Slow internet speed

• Cause buffering

• Corrupt transmitted data

Real-Life Example

You are at a concert with thousands of people.
Everyone is using mobile data.
Your internet becomes very slow because many signals are interfering with each other.

Multiple Choice

Interference happens when:

• Cables break

• Power goes off

• Radio waves mix together

• Data is encrypted

Attenuation (Signal Weakening)

Sometimes wireless signals do not get mixed — they simply become weaker.

This is called attenuation.

Attenuation happens when:

• Signals pass through walls

• Signals travel long distances

• Obstacles block the signal

It does not change data, but it weakens the signal strength.

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Real-Life Example

Your Wi-Fi works well in the living room but becomes weak in your bedroom because walls block the signa

Multiple Choice

Attenuation mainly causes:

• Data corruption

• Signal weakening

• Encryption

• Identity theft

Crosstalk

Crosstalk occurs in wired networks.

When many cables are close together:

• Electrical signals from one cable can affect another.

• This creates unwanted interference between cables.

Crosstalk can:

• Corrupt transmitted data

• Reduce signal quality

Modern cables are twisted or shielded to reduce crosstalk.

Real-Life Example

In older telephone systems, you could sometimes hear another conversation faintly on your call.

Multiple Choice

Crosstalk occurs when:

• Radio waves mix

• A hacker steals data

• A website is insecure

• Electrical signals interfere between cables

Hacking, Identity Theft & Fraud

A hacker is someone who tries to break into systems without permission.

If hackers steal your personal information:

• It is called identity theft.

If they use your information pretending to be you:

• It is called identity fraud.

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Real-Life Example

A hacker steals your email password.
They use it to reset your bank account password and steal money.

Multiple Choice

Using stolen personal information to pretend to be someone is:

• Crosstalk

• Identity fraud

• Attenuation

• Encryption

Protecting Yourself Online

To stay safe online:

✔ Use strong passwords
✔ Do not share personal information
✔ Check for HTTPS
✔ Avoid suspicious links

HTTPS means the website encrypts your data.

Look for:
🔒 Lock symbol
https:// at the beginning

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Real-Life Example

Before entering credit card details, check if the website address starts with https.

Multiple Choice

The “S” in HTTPS stands for:

• Safe

• Secure

• Server

• System

Why Encryption Is Important

Encryption:

• Scrambles data

• Makes stolen data useless

• Protects privacy

Even if hackers steal encrypted data, they cannot read it without the key.

Example encrypted sentence:
WKLV LV D PHVVDJH

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Real-Life Example

Online banking uses encryption to protect money transfers.

Multiple Choice

Encryption makes stolen data:

• Faster

• Larger

• Meaningless to hackers

• Visible

Activity 3.5 – Research Task

Research another cause of data errors.

Discuss:

• What did you find?

• How can errors be prevented?

Activity 3.5 – Research Task

Possible examples:

• Hardware failure

• Overheating

• Malware

• Network congestion

Multiple Choice

Which could also cause data errors?

• Strong passwords

• Hardware failure

• Encryption

• Encryption