Modelling Networks and Social Connections

Why We Connect People and Systems

🎯 (CT5-THI-01)

📌 Describe the purpose of connecting people and systems

A network is a group of devices, or people, that are linked so they can share information. A school’s group chat is a network. Everyone in it can send a message, and everyone else can read it.

Connecting people and systems is useful for four main reasons:

• To communicate. People can message, call or video chat, even when they are far apart. A grandparent in another city can see photos from a school concert.
• To share information. A team can keep one shared spreadsheet of training times. Everyone sees the same numbers.
• To share resources. Several laptops can print to one printer. This saves a school from buying a printer for every room.
• To use services and control things. You can check a bank balance, book a bus ticket or lock a smart door from your phone.

Connecting also brings risks. Every connection is a path that someone could misuse. The rest of this topic looks at both the benefits and the risks, so you can make good choices.

Inputs, Storage, Processes and Outputs

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📌 Describe inputs, storage, processes and outputs in connecting people and systems

Every connected system has four main parts. They are input, storage, process and output. The network is the link that carries data between these parts.

• Input is the data that goes into the system. Example: you type a message and tap Send.
• Storage is where data is kept so it can be used again. Example: a server keeps a copy of the message history. A server is a computer that stores data and shares it with other devices.
• Process is what the system does with the data. Example: it finds the right person, checks the message and passes it on.
• Output is what comes out of the system. Example: your friend reads the message, and their phone makes a sound.

Real-World Problems to Solve by Connecting

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📌 Define a real-world problem or need that can be solved by connecting people and systems, including breaking it down into manageable parts and describing the users of the solution

A problem statement says what is wrong, who it affects and what a good solution would do. You must define the problem before you design anything. A problem is not the same as a solution. “We need an app” is a solution. “Families miss training changes” is a problem.

To define a problem, follow three steps:

1. Write the problem in one or two sentences.
2. Break it down into smaller parts that you can solve one at a time. This is called decomposition.
3. Describe the users, the people who will use the solution, and what each one needs. A stakeholder is anyone affected by the solution, even if they never use it.

Functional Requirements and Test Cases

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📌 Specify the functional requirements of a networked solution, including stating the purpose of a solution, describing use cases and developing test cases of input and expected outputs

A functional requirement says what a solution must do. Each one starts with “The system must” and is specific enough to test.

Specifying has four steps:

1. State the purpose. Write one sentence saying why the solution exists.
2. Describe a use case. A short, step-by-step story of one user doing one task.
3. List the requirements. Number each one.
4. Write test cases. Each has an input (what is typed or pressed) and an expected output (what should happen).

Here are four test cases.

Write each expected output before you run the test. Otherwise you may accept a wrong result simply because you got it.

Non-Functional Requirements of a Network

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📌 Specify the non-functional requirements of a networked solution

• Cost of network hardware or data transfer.
• Social benefit or facilitating social interactions.
• Simple configuration and use for beginners.

A non-functional requirement says how well a solution must work, or what it must be like. It describes qualities, such as cost, how helpful it is to people and how easy it is to use. Where you can, write each one so that you can check it.

NESA gives three examples. Here is how each one could look for the netball messaging system.

Cost of network hardware or data transfer

The club has a set budget for the season. Some phone plans limit how much data you can use, so large files may cost families money. A possible requirement: the system must work on phones that families already own. A possible test: check the total cost of the solution against the committee’s budget.

Social benefit or facilitating social interactions

A good solution helps people feel connected. A parent might want to reply with a question, such as “Can we bring a lift?” A possible requirement: families must be able to reply to the coordinator, and the coordinator must see every reply. A possible test: send a reply from a test phone and check that the coordinator sees it.

Simple configuration and use for beginners

Some users are new to technology. Some coordinators use the system only once a season. A possible requirement: a parent who has never used the system must be able to read a message in three taps or fewer. A possible test: give the system to someone who has not used it before, and time how long they take.

Social, Ethical and Legal Responsibilities

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📌 Evaluate the social impacts and ethical and legal responsibilities in connecting people and systems

• Social: online access to services, remote working, cyber bullying, or the filter bubble.
• Ethical: black-hat and white-hat hacking, Digital Literacy codes of conduct, or protecting personally identifying information (PII).
• Legal: reporting data breaches to users and regulators, anonymising data and disposal of PII.

When people and systems connect, the effects reach beyond the technology. To evaluate them, sort the effects into social, ethical and legal groups.

Social impacts

• Online access to services. A person without internet access can be left out when services move online.
• Remote working. People can work from home, but they may find it hard to switch off.
• Cyber bullying. A mean message sent to a group can reach many people and is hard to remove.
• The filter bubble. Online services often show you more of what you already like, so you may see fewer different views.

Ethical responsibilities

• Black-hat and white-hat hacking. A white-hat hacker tests systems with permission to fix weak spots. A black-hat hacker breaks in without permission.
• Digital Literacy codes of conduct. A code of conduct is a set of rules for behaviour. Schools and clubs often have one for online use.
• Protecting personally identifying information (PII). PII is information that can identify a person, such as a full name and home address. Keep it private.

Legal responsibilities

• Reporting data breaches. A data breach is when personal information is accessed, copied or lost without permission. Under the Notifiable Data Breaches scheme in the Privacy Act 1988 (Cth), covered organisations must tell the Office of the Australian Information Commissioner (OAIC) and the people affected about breaches likely to cause serious harm.
• Anonymising data. This means removing or changing details so a person cannot be identified.
• Disposal of PII. Under the Australian Privacy Principles, an organisation that no longer needs personal information must generally destroy or de-identify it.

How to evaluate

Use criteria, such as who is affected, whether it is fair and whether it follows the law. Give evidence for both sides, then make a clear judgement.

Network Hardware: Wired, Wireless and Mobile

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📌 Describe common network hardware for wired, wireless and mobile networks

Network hardware is the physical equipment that lets devices connect. Networks can be wired, wireless or mobile. Each type uses different hardware, but all of them send data between devices.

• Wired networks use cables. A device connects with a network cable, often called an Ethernet cable.
• Wireless networks use radio waves. There are no cables between the device and the router.
• Mobile networks use the phone company’s network. A phone connects to nearby mobile towers. A SIM card is the small card in a phone that identifies it to the mobile network.

These are the common pieces of hardware you will meet:

• A network interface card (NIC) is the part that lets a device connect to a network. Most laptops and phones have one built in.
• A switch joins several wired devices so they can share a local network.
• A router sends data between networks, such as your home network and the internet.
• A modem connects your home to your internet provider’s line. Many home devices combine a modem and a router in one box.
• A wireless access point lets wireless devices join a wired network.

Network Security Risks and How to Reduce Them

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📌 Describe common network security vulnerabilities and the mitigation strategies

A vulnerability is a weakness that could be used to harm a network, its devices or the people who use them. A mitigation is a step that lowers the chance of a problem, or the harm it could cause. Think of a bike. A missing lock is a vulnerability. A good lock is a mitigation.

Good protection uses layers. This is called layered defence. If one layer fails, another still helps. For example, a strong password, regular updates and two-factor authentication (a password plus a second check, such as a code sent to your phone) work together.

Graph Theory in Network Models

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📌 Apply features of Graph Theory to model computer networks

Graph theory is a part of mathematics. It studies graphs, which are pictures made of dots and lines. A network can be drawn as a graph, so graph theory helps you model it and ask questions about it.

In a network model, each device is a node, drawn as a dot. Each connection between two devices is a link (also called an edge), drawn as a line. A line shows that the two devices can send data to each other directly.

Once a network is a graph, you can ask useful questions. Which device has the most links? Can every device reach every other device? Which device would cut off the most others if it stopped working? Sections later in this part answer these questions with numbers.

Node Degree and Paths Between Nodes

🎯 (CT5-DAT-02, CT5-COM-01)

📌 Calculate node degree and paths between nodes and explain their meaning

Once a network is a graph, you can measure it. Two useful measures are degree and path.

The degree of a node is the number of links that touch it. A link has two ends, so it counts towards the degree of two nodes.

A path is a route from one node to another, following the links. The length of a path is the number of links it uses. A shortest path is a path with the fewest links.

A high degree means a node is well connected, so the router, with the highest degree, is the most important node here. A degree of 1 means the node is at the end of a line. The printer’s only link goes through the router, so if the router fails, the printer is cut off.

Two paths mean the data has a backup route. If the router–laptop link breaks, data can still travel through the phone.

Social Networks as Graphs

🎯 (CT5-DAT-02, CT5-COM-01)

📌 Represent real-world social networks visually as a graph

• Social networks of friends, such as suggesting friends of friends as new connections.
• Kinship relationships of Aboriginal and/or Torres Strait Islander Peoples, with guidance from the local Aboriginal community.

A social network is a set of people and the connections between them. You can show it as a graph. Each person is a node, and each friendship is a link. This makes it easy to see who is connected to whom.

To represent a social network as a graph, follow four steps:

1. Decide what a node is. Usually, it is one person.
2. Decide what a link means. For example, “they are friends”.
3. Draw one node for each person.
4. Draw a link for each pair of people who are friends.

Friends of friends

Here is a small friend group of six people, A to F. A is friends with B and C. B and C are both friends with D. D is friends with E, and E is friends with F.

A and D are not direct friends. But they share two friends, B and C. Friends that two people share are called mutual friends. A simple rule could say: if two people have two or more mutual friends, suggest that they connect. So A and D could be suggested as new friends.

Kinship relationships

Kinship is the set of family relationships that show how people are connected. For many Aboriginal and Torres Strait Islander Peoples, kinship is central to identity and belonging. Kinship systems also differ between communities, so a kinship graph must be drawn with great care.

Kinship knowledge belongs to the community it comes from. This sits within Indigenous Cultural and Intellectual Property (ICIP). Indigenous Data Sovereignty is the idea that communities have the right to decide how their own data is collected, owned and used.

The syllabus asks you to work with guidance from the local Aboriginal community. Talk with the community before you draw, collect or share any kinship information. For practice, use a made-up group, not real family details.

Sociograms: Mapping Who Connects to Whom

🎯 (CT5-DPM-01, CT5-DAT-02)

📌 Evaluate the development of a sociogram model

A sociogram is a diagram of a group. Each person is a node. Lines or arrows show who is connected to whom. An arrow can show who chose whom, for example when a class is asked who they would like to work with.

The idea was developed in the 20th century by Jacob Moreno, a psychiatrist who studied how people in groups choose each other. Sociograms have changed since then. They were first drawn by hand, on paper. Today, software can draw one from a list of connections, and update it when the data changes.

Evaluate the development

To evaluate a sociogram, use criteria. Ask: Is it clear? Is it accurate? Does it respect people’s privacy? Does it help or harm people? Is the data up to date?

• Strengths. A sociogram is quick to read. It shows who is in the middle of a group, and who is on the edge with no links at all.
• Limits. It shows that two people are connected, but not why. It can be wrong if the data is out of date or the question was unclear.
• Risks. A sociogram of people can hurt them. If it labels someone as unpopular, that person may feel left out.

Judgement: a sociogram is a useful model for understanding a group. It works best when people agree to take part, the results are kept private, and it is used to help the group rather than to rank or label people.

Changing Expectations of Security and Privacy

🎯 (CT5-SAF-01, CT5-EVL-01)

📌 Explore how people’s changing expectations and concerns for security and privacy have shaped computer technology

• Identity verification in online environments, such as considering cyber safety before connecting with someone.
• Using appropriate firewall settings, such as implementing cyber security to browser software.
• Setting up a Virtual Private Network (VPN).
• Researching the evolution and innovation of interactive sharing solutions.
• Remote working and learning via collaboration applications.

Early on, people shared files by carrying a floppy disk or USB drive to another computer. Sharing then grew into email, chat, video calls and shared documents, and new worries came with it. Who can see my messages? Can I trust the person I am talking to?

Each worry pushed technology in a new direction. Concern about who is really online led to identity verification, which checks that a person is who they say they are. Concern about unwanted visitors led to firewalls. Concern about private work away from the office led to VPNs.

Identity verification

A code sent to your phone is one common way to verify identity. Before you connect with someone online, check who they are. Never share a password or verification code, even with someone who says they are from your school.

Firewall settings

A firewall checks the traffic going in and out of a device or network, and blocks anything its rules do not allow. Keep it turned on. Browsers have settings too, such as blocking pop-up windows.

Virtual private networks (VPNs)

A virtual private network (VPN) makes a private, scrambled link between your device and a VPN server. Others on the same network cannot easily read it. A VPN does not make you invisible. The VPN provider can still see some information about your traffic.

Many people now work and learn through collaboration apps, which let people share files, chat and meet online.

Diverse Perspectives on Networks and Connections

🎯 (CT5-DES-01, CT5-SAF-01)

📌 Explore network and social connections considering the perspectives of diverse groups, including Aboriginal and Torres Strait Islander Peoples, culturally and linguistically diverse people, people of different ages and gender, and people with disability

A network that works for one group can fail another. A design that suits a Year 12 student may frustrate a grandparent. To explore different views, ask people from each group what they need. Who gains, and who is left out?

As with kinship data in Part 1, the community decides how its information is used, not the designer.

Access Control and Data Movement

🎯 (CT5-DAT-01, CT5-SAF-01)

📌 Investigate how hardware and software are used to manage, control and secure the movement of, and access to, data in networked digital systems

Access control decides who can see, change or send data. Data movement is how data travels between devices. Tools for both can be hardware (physical equipment) or software (programs).

End User Profiles and Attributes

🎯 (CT5-DES-01, CT5-THI-01)

📌 Investigate how the profile and attributes of end users are used by developers when creating products

• Cultural connection, such as Aboriginal and/or Torres Strait Islander participants in a range of contexts.
• Accessibility needs, such as vision and hearing.

A user profile describes the people who will use a product. Its attributes are the features of those people that matter for the design, such as age, goals, language, device, ability, culture and internet access. Developers use profiles to make choices. Should the text be large? Should it work on a slow connection?

Many teams write a short story about one typical user. This is called a persona. It helps a team picture a real person while they design.

Cultural connection

Cultural connection is how a person’s culture, language and community shape the way they use technology. For Aboriginal and Torres Strait Islander participants, this might affect which images, words and sharing choices feel respectful. Work with the community, not just for it. Use images or stories only with permission.

Accessibility needs

An accessibility need is something a person needs in order to use a product well. Two common examples:

• Vision: large or adjustable text, strong contrast, and a screen reader that reads the screen aloud.
• Hearing: captions on videos, and visual alerts as well as sounds.

Iterative Project Management for Connections

🎯 (CT5-DPM-01, CT5-COL-01)

📌 Plan and manage a project that connects people and systems using an iterative approach, including access control, privacy and cybersecurity

To plan a project is to decide what you will make and in what order. To manage it is to check progress and change the plan when something goes wrong. Many teams use an iterative approach. This means building the project in small rounds, called iterations.

Each iteration follows the same steps:

1. Plan one small goal for the round.
2. Build that part.
3. Test it against what you wanted.
4. Review what worked and what did not.

Each round starts with what you learned, so problems show up early.

Plan these three things from the start, not at the end:

• Access control decides who can see or change what. In the netball club, families can read messages, but only the coordinator can send them.
• Privacy means keeping only the personal details you need, and keeping them safe.
• Cybersecurity protects the system from misuse. Strong passwords are a simple example.

Keep the plan written down, with each iteration’s goal and test beside it.

Alternative Designs and Final Choice

🎯 (CT5-DPM-01, CT5-THI-01)

📌 Generate alternative designs and evaluate them against the requirements to select a preferred design

A design is a plan for how a solution will work. An alternative design is a different plan for the same problem. Your first idea is rarely the only good one, so sketch at least two designs before you choose.

Work through these steps:

1. Write your requirements, so you know what the design must do.
2. Sketch at least two different designs.
3. Compare each design against each requirement.
4. Select the preferred design: the one that best meets your most important requirements.

Judgement: Design B meets both must-have requirements, access control and privacy. Design A is quicker to start. Design B is the preferred design, and a simple guide to logging in can reduce its extra effort.

Networks Between Multiple Devices

🎯 (CT5-DAT-01, CT5-DPM-01)

📌 Create a computer network between multiple devices and describe how nodes are connected

A node is any device on a network. A link is a connection between two nodes. When you build a network, you decide which nodes exist and how each one links.

Build a small network in this order:

1. List the devices. Each device is a node.
2. Decide how each device connects: by cable (wired) or by radio waves (wireless).
3. Link each device to the router, or to a switch that links to the router. A switch joins several wired devices so they can share one local network.
4. Name each node, so you can tell them apart.
5. Test that the devices can reach each other.

Only build networks with devices you own or have permission to use. Ask your teacher before changing a school network.

Internet of Things (IoT) Networks

🎯 (CT5-EVL-01, CT5-DAT-01)

📌 Create a network of connected devices to model the Internet of Things (IoT)

The Internet of Things (IoT) is a name for everyday objects that connect to a network and share data. Many IoT objects have a sensor, which detects something such as temperature or light. Some also have an actuator, which does something, such as opening a valve or turning on a light.

You can model an IoT system as a network of nodes:

• Sensors send readings.
• A hub receives the readings and decides what to do.
• Actuators carry out the hub’s commands.
• A user checks the system on a phone or computer.

Some IoT devices come with a default password. Change it, and install updates when they are offered.

Turning the Design into a Solution

🎯 (CT5-DPM-01, CT5-DAT-01)

📌 Implement a solution that connects people and systems using the preferred design

• Connecting and configuring devices in a simple network.
• Modelling and collecting data for a social network, such as kinship relationships of Aboriginal Peoples.

To implement a solution is to build the preferred design, step by step. Check each step before you move on, and note what you did.

NESA gives two examples.

Connecting and configuring devices in a simple network

To configure a device is to set its options, such as its name and password. Follow these steps for a made-up home or club network:

1. Set up the router using the guide that came with it. Ask an adult to check the power and cables.
2. Give the network a name and a new strong password. Change any default password.
3. Connect each device and check it joins.
4. Name each device, such as “Coordinator-Laptop”.
5. Test: each device should reach the router, and the coordinator’s laptop should reach the printer.

Modelling and collecting data for a social network

NESA’s example is the kinship relationships of Aboriginal Peoples. This needs great care. Kinship knowledge belongs to the community it comes from. It connects to Indigenous Cultural and Intellectual Property (ICIP). It also connects to Indigenous Data Sovereignty. This is the idea that communities have the right to decide how data about them is collected, owned and used.

Before you collect anything, work with the local Aboriginal community. Your teacher can help you make contact. Ask what should be collected, why, who will hold it and who may see it.

For class practice, use a made-up group with neutral labels, such as Person A and Person B. Label each link “Link 1” or “Link 2”. The real labels must come from the community. Store the data privately, and share only what the community approves.

Interactive Pages for Sharing Information Online

🎯 (CT5-OPL-01, CT5-DES-01)

📌 Create interactive solutions for sharing information online using a visualisation library

An interactive solution reacts to what the user does. A button, a drop-down list or a filter can change what is shown. A visualisation library is a ready-made set of code for drawing charts. You reuse it, rather than building every chart from scratch.

Create an interactive page like this:

1. Choose the information to share. Use made-up data, such as weekly attendance for three teams.
2. Choose a visualisation tool or library your teacher approves. Read its licence first.
3. Draw one chart from the made-up data. Add a title and a label for each axis (a line on the edge of a chart that shows the scale).
4. Add one interaction, such as a drop-down list that shows one team at a time.
5. Test each choice. Check that it shows the right numbers.
6. Credit the library and its authors on the page.

Keep personal data off the page. If the data is about real people, a public page can reveal it. Use team totals or made-up names instead.

Data Collection, Ownership and Protection

🎯 (CT5-SAF-01, CT5-DAT-01)

📌 Specify what data is collected, who owns it, and how it will be protected, considering privacy and cybersecurity, including when interpreting data

A data specification is a written plan. It says what data you will collect and what you will do with it. It answers four questions: What data do we need? Why do we need it? Who owns it? How will it be protected? It also says how long the data will be kept.

Ownership means who has the right to decide how the data is used. Personal information describes a real person, who has privacy rights. The organisation that holds it must look after it.

Here is a specification for a class survey about favourite sports.

Notice that the name is left out. If you do not need a piece of data to answer your question, do not collect it.

Be careful when you interpret the results. A survey of one class does not show what the whole school thinks. A small group can also mislead, because a few answers can change a percentage a lot.

Data Types, Storage and Transmission

🎯 (CT5-DAT-01, CT5-DAT-02)

📌 Represent, store and transmit data to facilitate computation, including selecting appropriate data types, understanding the limitations of data types and structuring data systematically

Computers store all data as bits. A bit is a single 0 or 1. Eight bits make one byte. To store data well, you choose a data type that fits it. A data type tells the computer what kind of value to expect.

The limitation is the important part. A product code such as 00742 looks like a number. If you store it as an integer, the computer drops the leading zeros and shows 742. Store codes like this as text instead.

# Numbers add; text joins
print(12 + 3)       # 15
print("12" + "3")   # 123, because the text is joined, not added

Store data in a table. Each column is a field, such as name or goals. Each row is one record, such as one player. Every value in a field should be the same type.

When data is sent across a network, it travels as bits. More bits take longer to send, so choosing a small, correct data type helps.

How Data Compression Affects Transmission

🎯 (CT5-DAT-01)

📌 Explain simple compression of data and types of compression, including the impact on data transmission

Compression makes a file smaller. Smaller files take less time to send and use less of your data plan. There are two main ways to compress. Some methods find repeated patterns and write them more briefly. Others remove detail that you may not notice.

• Lossless compression keeps all the information. The original file can be rebuilt exactly. It is used for text, school documents and computer code.
• Lossy compression removes some information that people are unlikely to notice. The file gets much smaller, but the original cannot be rebuilt exactly. It is used for photos, music and video.

A simple lossless method is run-length encoding. It replaces each run of the same letter with a count and the letter. So WWWWWWBBBW becomes 6W3B1W.

# Run-length encoding: write each run as a count, then the letter
def compress(text):
    result = ""
    i = 0
    while i < len(text):
        count = 1
        # count how many times the same letter repeats in a row
        while i + count < len(text) and text[i + count] == text[i]:
            count = count + 1
        result = result + str(count) + text[i]
        i = i + count
    return result

print(compress("WWWWWWBBBW"))   # prints 6W3B1W

Compression changes how data is transmitted. A smaller file has fewer bits to send, so it usually arrives sooner. But compressing and decompressing takes work, so it is a trade-off.

Entities, Events and Relationships

🎯 (CT5-THI-01, CT5-DAT-02)

📌 Model entities, events and relationships within a network

An entity is a thing you store information about. It might be a person, a team, a device or a place. Its attributes are the details you record about it, such as a name or a training day.

An event is something that happens at a point in time, such as a message being sent or a training session being moved. A relationship shows how two entities or events are linked, such as “a player belongs to one team”.

Store only the details you need. A real phone number is not needed for a class model, so use made-up contacts.

Relational Data and Linked Tables

🎯 (CT5-DAT-02, CT5-DAT-01)

📌 Model the relationships between entities and events using relational data

Relational data is data stored in separate tables that are linked to each other. Each table holds one kind of entity or event. Storing data this way means you do not repeat the same information many times.

Two kinds of key make the link work:

• A primary key is a field with a unique value for each record, such as a TeamID.
• A foreign key is a field that holds the primary key of a record in another table, such as the TeamID in the changes table.

To find which team’s training changed in Week 3, follow these steps. Find the row for Week 3, which is C1. Read its TeamID, which is T1. Look up T1 in the teams table. It is the Hawks.

Why not write the team name in every change row? You could. But if the name is typed wrongly once, the two copies disagree. A link with a key keeps one correct copy of the name.

Project Records and Iterative Design

🎯 (CT5-COL-01, CT5-DPM-01)

📌 Create a record of project development demonstrating iterative design and evaluation

A project record shows how your project changed over time. It is a log of what you planned, built, tested and changed, and why. A good record shows iterative design, where you improve the solution in rounds using test results. It also shows evaluation, where you judge each round against your requirements.

To build your own record:

1. Start the record on day one, not at the end.
2. Write after each iteration, while you still remember what happened.
3. Record failed tests as well as passed ones. Failures show what needs fixing, so they are strong evidence.
4. Link each change to a test result or to a requirement.

Specialist Terms in Context

🎯 (CT5-COM-01)

📌 Select and use specialist terminology in context

Specialist terms are words with a precise meaning in computing, such as node, query or lossy. Using them correctly shows that you understand the idea. Using them in a sentence shows what they mean in that context.

To use a term well:

1. Know its meaning. Check the glossary page on this site if you are unsure.
2. Use the term in a sentence that makes its meaning clear.
3. Check that you have not used it for something else.

A stronger sentence is not always longer. It is more exact. Words such as field and record have precise meanings that everyday words do not have.

Responsible Data Collection and Access

🎯 (CT5-SAF-01, CT5-DAT-02)

📌 Access datasets and collect data from users or the environment considering privacy and personally identifying information (PII)

A dataset is a collection of data put together for a purpose. You can access a dataset that someone else has published, or you can collect your own. Either way, think about privacy, which is a person’s right to control their own information.

Personally identifying information (PII) is any information that can identify a person. Examples include a full name, a home address, a date of birth, a photo and an email address. Be careful with combinations. A school name and a year group together can sometimes be enough to work out who someone is.

Data can also come from the environment. A temperature sensor in a school garden records readings. These readings hold no personal information, so the privacy risk is low.

If someone shares a dataset with you, check its licence or terms of use before you use or publish it.

Practise on this made-up dataset. It records visits to three pretend parks.

Data Validation and Invalid Data

🎯 (CT5-DAT-02, CT5-THI-01)

📌 Validate data is correct and investigate the impact of invalid data

Validation is a check that data follows a rule before it is accepted. Validation does not prove that data is true. It only checks that the data looks right. A score of 10 may pass a check and still be a typing mistake for 100.

Common checks include:

• Presence check: is something typed in?
• Type check: is it the right kind of value, such as a number?
• Range check: is it between the allowed limits?
• Length check: is it the right number of characters?
• Lookup check: is it on an approved list, such as a list of team names?

This short program checks game scores. A made-up rule says a score must be from 0 to 100.

# A made-up rule: a game score must be from 0 to 100
def check_score(score):
    if score < 0 or score > 100:   # range check
        return "Invalid: score must be from 0 to 100"
    return "Valid"

print(check_score(45))    # Valid
print(check_score(450))   # Invalid: score must be from 0 to 100

Invalid data can cause real harm. A score of 450 instead of 45 makes a team’s average look far too high. A wrong phone number can send a private message to the wrong person. Check data before you use it to make a decision.

Data Analysis, Decisions and Reports

🎯 (CT5-DAT-02, CT5-COM-01)

📌 Analyse data to make decisions and generate reports using a database

Analysing data means looking at it to find patterns, compare groups and answer a question. A report then presents your findings to an audience, such as a coach or a club committee. A database helps, because you can select exactly the rows you need.

The examples in this part use this made-up table of netball players. The table is called players. Each row is one record. Sessions means training sessions attended.

The coordinator asks: which players scored 10 or more goals this season? Ask the database with this query:

SELECT name, goals FROM players WHERE goals >= 10 ORDER BY goals;

The result is Dev with 12, Ava with 18 and Chloe with 25. The next section explains each word in the query.

Now read the result carefully. Three players scored 10 or more goals. But goals alone do not show how often each player was at training. Chloe attended the most sessions. Dev attended fewer sessions than Ava. A fair report would say so.

Write the report in a short, clear form: the question, the data used, the method, the finding, one limit and a suggestion. A decision about people should be fair, so use the whole season, not one game.

Database Queries and Their Clauses

🎯 (CT5-DAT-02, CT5-OPL-01)

📌 Filter, sort and limit database queries using SELECT, WHERE, ORDER BY and LIMIT clauses

A query is a question you ask a database. You write it in SQL, short for Structured Query Language. A query can filter rows, sort them and limit how many you see. Each keyword that shapes a query is called a clause. These are the words to know:

Inside WHERE, the symbols = (equal to), > (more than), < (less than) and >= (more than or equal to) compare values. Some database tools use a different word from LIMIT, so check your tool.

This query shows the name and goals of each Hawks player:

SELECT name, goals FROM players WHERE team = 'Hawks';

The result is Ava (18), Chloe (25) and Eli (3). Text goes in single quotation marks. Numbers do not.

This query finds the two players with the fewest goals:

SELECT name, goals FROM players ORDER BY goals LIMIT 2;

The result is Eli (3) and Ben (7). This query uses AND, so both conditions must be true:

SELECT name, team FROM players WHERE team = 'Owls' AND goals > 5;

The result is Ben and Dev. Without ORDER BY, rows may come back in any order.

Keeping a Database Up to Date

🎯 (CT5-DAT-02, CT5-DAT-01)

📌 Load, insert and update data in a database

A database is only useful when it is up to date. You can load many records at once, insert one new record, or update records that have changed.

• Load brings in data from a file, such as a list exported from a spreadsheet as a CSV file. A CSV file is plain text, with commas between the values.
• Insert adds a new row.
• Update changes the values in rows that already exist.

To load a file safely, follow these steps:

1. Check that the columns in the file match the fields in the table.
2. Check the types. A word in a goals column is a problem.
3. Keep a copy of the original file.
4. Load the file, then count the rows. The count should match the file.

To add Finn, who plays for the Owls with 4 goals and 5 sessions, use this command:

INSERT INTO players (name, team, goals, sessions) VALUES ('Finn', 'Owls', 4, 5);

To change Ben’s goals from 7 to 9, use this command:

UPDATE players SET goals = 9 WHERE name = 'Ben';

VALUES and SET are small extra words that these two commands need to be complete.

Data Visuals: Trends, Patterns and Outliers

🎯 (CT5-DAT-02, CT5-DES-01)

📌 Visualise data to identify trends, patterns, relationships and outliers using a range of tools

Visualising data means showing it as a picture, so the story is easy to see. Pictures can show trends (a general direction over time), patterns (things that repeat), relationships (two things that change together) and outliers (values far away from the rest).

Choose a chart that fits the question:

• Line chart: shows change over time, such as weekly attendance.
• Bar chart: compares categories, such as goals for each player.
• Scatter plot: shows the relationship between two numbers, such as sessions and goals.

1. Choose a chart. A line chart, because the data changes over time.
2. Draw it with a title and labelled axes.
3. Look for a trend. Apart from week 5, the numbers stay between 8 and 11, with no clear rise or fall.
4. Look for an outlier. Week 5, with 3 players, is far below the others.
5. Check before you explain. Could week 5 be a data-entry mistake? Look at the notes. Do not guess.

To look for a relationship, use a scatter plot. Each player is one point: sessions across, goals up. In the made-up table, players with more sessions tend to have more goals. This does not prove that attending more sessions causes more goals.

Solution Quality Against Requirements

🎯 (CT5-DPM-01, CT5-SAF-01)

📌 Evaluate solutions against the predetermined functional and non-functional requirements that meet social, ethical and legal responsibilities and cybersecurity principles

To evaluate a solution, compare what it does with what it must do. Use the requirements you wrote in Part 1. Turn each one into a test, run the test and record what happened. Then make a judgement about the result.

Write the expected result before you run the test. Then you cannot change your mind about what should have happened, just to match the result you got.

Judgement: the app meets its sending and privacy requirements. It fails the requirement for simple use, because a new parent needs too many taps. The team should change the screen so a message opens in three taps or fewer, then test again.

Navigation Maps and Their Efficiency

🎯 (CT5-DPM-01, CT5-DES-01)

📌 Test and evaluate the efficiency of a network navigation map

A navigation map shows the screens in a solution and the links that take a user from one to another. It is a graph, like the ones in Part 1. Each screen is a node, and each link is a line.

Efficiency means reaching a goal in as few steps as makes sense for the user. A step is one tap, click or link. Fewer steps usually help, but only if the user can still find the way.

To test a map:

1. Choose a task people do often, such as finding a training time.
2. Find the path from the start screen to the goal on the map.
3. Count the links on the path. This is the number of steps.
4. Ask a real user to do the task. Count their taps and note where they hesitate.

Suppose three test users each took a wrong turn at Settings. A direct link from Home to Contact would cut the third task to one step. Test again, and check that the other tasks still work.

Network Performance and Reliability

🎯 (CT5-DPM-01, CT5-DAT-01)

📌 Test, monitor and evaluate a network in terms of bandwidth, connectedness, compatibility, reliability and ease of use

A network can work on the day it is set up, then slow down or drop out later. To monitor a network, check it over time. Test these five measures.

Speed alone is not enough. A fast connection that drops out every evening is not reliable.

Network Resistance to Attacks

🎯 (CT5-SAF-01, CT5-DAT-01)

📌 Evaluate the security of networks in terms of vulnerability to attacks and exploitation

A vulnerability is a weakness. Exploitation means taking advantage of a weakness to cause harm. To evaluate security, find the weaknesses, then judge how serious each one is. You do not need to attack anything to do this.

Start with a checklist. A network with all five in place is in a much better position than one with none.

• The router’s factory password has been changed to a strong one.
• Devices and software are kept up to date.
• A firewall is turned on.
• Important accounts use two-factor authentication.
• Visitors use a separate guest network, if the router offers one.

Then judge each weakness by its likelihood (how likely it is to be used) and its harm (how much damage it could do). Together these give a risk, a judgement of how serious the weakness is.

Judgement: the shared password is the most likely to be misused and would cause the most harm, so it comes first. A network is only as safe as its weakest point.

Careers in Connecting People and Systems

🎯 (CT5-EVL-01)

📌 Explore careers in connecting people and systems

Many jobs involve connecting people and systems. Some people build networks. Others keep them safe, design how people use them or study the data they produce. Your school’s careers adviser can tell you more about any of these roles.

Job titles and duties differ between employers. Treat this table as a starting point, and check each role before you decide. To explore a career, look at three things: what the work involves each day, what skills it needs and what study or training it may need.