Object-Oriented Programming

Learning Objectives

• Describe the network interface card and the MAC address.
• Compare a hub, a switch and a router.
• State the role of the main internet protocols.
• Trace how a typed web address becomes a displayed page.

Starter Scenario

The ICT teacher brings a small circuit board to class and says, 'Without this tiny card inside every computer, no computer could join a network, no matter how many cables or routers you have.' The card is a Network Interface Card, or NIC. It is the essential hardware component that enables a device to connect to a network. Without a NIC, even the fastest router and the best internet connection would be useless, because the computer would have no means to send or receive data.

Network Devices in Depth

A Network Interface Card, or NIC, is a hardware component, either built into the motherboard or inserted as an expansion card, that allows a device to connect to a network. Every NIC has a unique address called a MAC address, which stands for Media Access Control address, and this identifies the device on the network. When a computer sends data, the NIC converts the data into electrical signals for wired networks or radio waves for wireless networks and places them on the network cable or airwaves.

A hub and a switch both connect multiple devices, but they work differently. When a hub receives data, it sends a copy to every connected device, even if the data is only meant for one device. This creates unnecessary traffic and reduces efficiency. When a switch receives data, it reads the destination address and sends the data only to the intended device. This is faster, more efficient and more secure. Because of this difference, switches have largely replaced hubs in modern networks. In a school laboratory, a switch would connect 30 computers and ensure each one receives only the data meant for it.

A router reads the destination IP address and forwards data between different networks. It is more intelligent than a switch because it decides the best path for data to travel across multiple networks. A modem converts digital data from a computer or router into a format suitable for transmission over telephone lines, cable lines or fibre optic lines. It also converts incoming signals back into digital data. The word modem comes from modulator-demodulator. An access point allows wireless devices such as phones, tablets and laptops to connect to a wired network using Wi-Fi. Without an access point, wireless devices cannot join the school's LAN. In many home and school setups, the modem, router and access point are combined into one device, but they perform three different functions.

Network Protocols

Two students in the same classroom speak different languages. One speaks only English and the other speaks only Hausa. Without a common language, they cannot communicate. Networks face the same problem when devices from different manufacturers, countries and operating systems need to talk to one another. The solution is a protocol, a set of rules that all devices agree to follow. Just as speakers of different languages can communicate through a shared language or translator, devices on a network communicate through shared protocols that define how data is formatted, addressed and transmitted.

A protocol is a set of rules and standards that govern how data is formatted, transmitted, and received across a network. Protocols ensure that devices from different manufacturers and running different software can communicate reliably. Without protocols, network communication would be chaotic. One device might send data too fast, another might not understand the format, and a third might not know where to send the response. Protocols solve all of these problems.

TCP/IP

TCP/IP stands for Transmission Control Protocol and Internet Protocol. It is the set of core protocols that makes the internet work. TCP/IP is actually two protocols working together. IP, the Internet Protocol, is responsible for addressing and routing packets. It assigns each device an IP address and ensures packets are sent to the correct destination across multiple networks. TCP, the Transmission Control Protocol, is responsible for reliability. It breaks data into packets, numbers them, sends them, and checks that all packets arrive correctly. If any packet is lost, TCP requests retransmission. Together, TCP and IP ensure that data reaches the right place, in the right order, without errors. Every web page, email, video call and file download relies on TCP/IP.

IPv4 means the older internet address system with four numbers.

HTTP and HTTPS

HTTP, which stands for HyperText Transfer Protocol, is the protocol used by web browsers to request and receive web pages from web servers. When you type a URL and press Enter, your browser sends an HTTP request to the server, which responds with the web page. HTTPS, which stands for HyperText Transfer Protocol Secure, is the secure version of HTTP. It adds encryption, meaning the data between your browser and the server is scrambled so that third parties cannot read it. HTTPS is essential for any activity that involves personal data, such as logging into accounts, online banking, or entering personal information. Websites that use HTTPS show a padlock icon in the browser address bar.

DNS and Putting It All Together

DNS stands for Domain Name System. When you type a domain name into your browser, your browser first checks its own cache to see if it already knows the IP address for that domain. If not found, the request goes to your operating system's cache. If still not found, the request is sent to a DNS resolver, usually provided by your ISP. The DNS resolver queries a series of DNS servers in order, first the root server, then the top-level domain server such as.com or.ng or.edu, and finally the authoritative name server for that domain. The authoritative server returns the correct IP address to the resolver. The resolver sends the IP address back to your browser, which then connects to the web server and loads the page. This entire process typically takes less than one second, even though it may involve several servers across different countries.

Consider a complete scenario. Amina in Abuja types www.news.ng into her Chrome browser and presses Enter. Amina's NIC sends the request as a signal through the school's network cable to the switch. The switch forwards the request to the school's router. The router sends the request to the ISP via the modem. The ISP's DNS resolver finds the IP address for www.news.ng using DNS protocols. The request, formatted as an HTTPS request using TCP/IP, travels across multiple networks to the news.ng web server. The server responds with the web page, encrypted using HTTPS. The packets travel back through the same chain, reassembled by TCP, and the browser displays the page. Every device and every protocol plays a specific role in this journey.

The Digital Economy: Old Ways versus New Ways

Before the internet, buying and selling happened mostly in physical markets, shops and offices with cash payments, printed receipts and paper records. The digital economy changed this by letting people buy, sell and transact through computers and phones connected to networks. E-commerce (buying and selling online) lets a customer order goods on a marketplace such as Jumia or Konga from anywhere in Nigeria, and online services include internet banking, airtime top-up and e-learning platforms. These services depend on the network devices and protocols studied this week.

Old economy: physical shops, cash payments and paper records.

New economy: online marketplaces, mobile transfers and electronic receipts.

E-commerce platforms such as Jumia and Konga connect buyers and sellers online.

Digital Literacy and Responsible Digital Citizenship

Digital literacy is the ability to find, evaluate, create and communicate information using digital tools. It includes searching the web effectively, judging whether a source is trustworthy and protecting personal information. Responsible digital citizenship means using technology safely and respectfully, such as not sending hurtful messages, not sharing false information and keeping passwords private. In Nigeria, the NDPR protects personal data, so learners should think before sharing sensitive details online.

Compare at least two sources before trusting online information.

Keep passwords private and never share them.

Avoid cyberbullying and report harmful messages.

Respect the NDPR by handling personal data carefully.

Intellectual Property, Copyright and Respecting Creative Work Online

Intellectual property is a creation of the mind with value, such as a song, a film, a book, a photograph or a software program. Copyright is the legal protection that gives the creator control over how their work is copied and shared. In Nigeria, the Nigerian Copyright Commission enforces these rights. Copying or downloading protected work without permission is piracy, while citing the source when quoting a writer or artist shows respect. Learners should always submit their own work and credit any borrowed ideas.

Intellectual property covers songs, films, books, photos and software.

Copyright gives the creator control over copying and sharing.

Piracy, copying protected work without permission, breaks the law.

Cite sources when quoting the work of another person.

Practical Work

1. Write one sentence on what each of the NIC, hub, switch, router and modem does.
2. Draw a table comparing HTTP and HTTPS.
3. List the steps a browser takes to load a named website.
4. Explain, using an example, why a switch is better than a hub.

Scenario-Based Questions

1. A school buys a new desktop computer. The ICT teacher says it cannot join the network without a NIC. What is a NIC, where is it located inside the computer, and what does it do?
2. A cybercafe has 20 computers connected by a hub. Customers complain that the network is slow. Explain why a hub causes delays when many computers send data at the same time, and suggest a better device to replace the hub.
3. Amina types www.news.ng into her browser. Trace the full journey of how her browser turns this name into data she can read, naming at least three devices or services involved.
4. A government office sends secret reports over the internet. The ICT officer insists on using HTTPS instead of HTTP. Explain the difference between the two and why it matters for secret documents.
5. A school network has a router, a switch and a modem. A new teacher asks what each device does. Explain the role of each device in one sentence.
6. A data packet leaves Computer A in one building and must reach Computer B in another building on a different network. Describe the role of the router in getting this packet to its destination.
7. A pupil says DNS is the same as IP address. Write a short correction explaining what DNS does and what an IP address does, and why both are needed.

Lesson objectives

By the end of the week, learners should be able to:

1. Define object, class and instance in their own words.
2. Name at least three object attributes and methods.
3. Create a simple class with one attribute and one method.
4. Instantiate an object and call its method.
5. Explain why OOP helps larger software teams.

Key vocabulary

• Object: an instance tied to data and behaviour.
• Class: a blueprint defining object attributes and methods.
• Instance: one concrete object created from a class.
• Attribute: data held inside an object.
• Method: behaviour belonging to the object.
• Instantiate: creating a concrete object from a class.
• Blueprint: the structural template a class provides.
• Data and behaviour: attributes and methods together.
• Team: a group of developers building software together.

Common misconceptions

• "Objects are the same as variables." Objects bundle data and behaviour; variables hold single values.
• "Classes store actual data." Classes describe structure; instances hold data.
• "OOP replaces procedural programming." OOP complements procedural styles when scaling to large teams.

Teacher activities

1. Starter: display a class diagram on the board and ask what it represents.
2. Define object, class and instance one by one with worked examples.
3. Name object attributes and methods as a class brainstorm.
4. Create a simple class with one attribute and one method.
5. Instantiate an object and call its method step by step.
6. Close with the team-scale explanation and exit question.

Student activities

1. Answer the starter and describe what the class represents.
2. Define object, class and instance in their own words.
3. Name at least three object attributes and methods from their own experience.
4. Create a simple class with one attribute and one method.
5. Instantiate an object and call its method with the correct arguments.
6. Explain why OOP helps larger teams in one paragraph.
7. Answer the exit question comparing OOP with procedural style in one sentence.

Practical / learning evidence

A one-class definition sheet, a class skeleton with attribute and method declarations and an instantiated object demonstration. Submit all three for marking.

Resources and preparation

Computers with an OOP interpreter or modern Python available, blank templates and sample class names. Provide a prebuilt interpreter in a read-only folder if one exists. Disable Caps Lock before typing.

Assessment for learning

Inspect the class definition for correct attribute and method naming. Check the instantiated object call for matching arguments. Ask a learner to explain why OOP helps large teams. Flag any learner who treats classes as data holders.

Inclusion and homework

Provide the class template prefilled for attribute and method names and allow oral instantiation. Extend confident learners with two objects and a second class-method demonstration. Homework: describe one real application built with object-oriented principles in one paragraph.