Unit 4
Term 3 (10 weeks)
Builds on Unit 3 by developing software solutions, programming skills, and networking concepts. Students apply the software development cycle (SDC), create algorithms, and explore network communications.
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Developing Software
Theory First: Developing Software
Before test preparation, build the theory. Work through these concepts, explain them in your own words, then apply them to a realistic school software scenario.
Theory focus 1
Software Purpose and Software Types
Explain how software gives instructions to hardware and classify software by its purpose.
Theory focus 2
Operating Systems
Explain the role of an operating system in managing hardware, files, users, security and applications.
Theory focus 3
Utility Software
Explain file compression, defragmenter, anti-virus and anti-malware using accurate use cases.
Theory focus 4
Software Licensing
Compare freeware, open source and shareware and explain licence compliance in school scenarios.
Theory focus 5
Software Development Cycle
Describe and apply the SDC stages: state the problem, plan and design, develop, test and evaluate.
Theory focus 6
User Needs and User Interface
Identify user needs and justify user interface decisions using the user, task, device and environment.
Developing Software
Software Types
Operating Systems
Manage hardware and software resources
Examples: Windows, macOS, Linux
Utility Software
Maintenance tools
Examples: Compression, defragmenter, anti-virus, anti-malware
Application Software
Task-focused programs for users
Examples: Word processors, spreadsheets, games
Software Licensing
Freeware
Free to use, no source code
Open Source
Free, source code available
Shareware
Trial period, then pay
Software Development Cycle (SDC)
The SDC is a structured process for developing software solutions.
The cycle may return to earlier stages for revision
Programming
Data Types and Variables
Whole numbers
42, -7, 0 Decimal numbers
3.14, -2.5 True or false
true, false Single character
'A', '7', '$' Control Structures
Sequence
Instructions executed one after another
Selection
Decisions (IF-THEN-ELSE)
Iteration
Loops (WHILE, REPEAT UNTIL, FOR)
Example Pseudocode
total <- 0
for i <- 1 to 10
if scores[i] >= 50 then
total <- total + scores[i]
endif
endfor Validation and Testing
Test Data Types
Normal
Expected valid input
Boundary
Edge case values
Invalid
Incorrect input
Trace Table Example
| Input x | Condition x > 5 | Output |
|---|---|---|
| 4 | false | "small" |
| 7 | true | "large" |
Common Mistake: Only testing with valid inputs. Always include boundary and invalid test data.
Networks and Communications
Networks are scenario questions
The aim is not just naming hardware. Students need to explain why a device, topology, medium, protocol, or protection method suits a realistic situation.
Answer pattern
- Name the correct concept.
- Define its role accurately.
- Apply it to the scenario.
- Mention a limitation when comparing choices.
Network Hardware
Router vs switch, modem, firewall, NIC, wireless access point, hub and bridge with school-network examples.
Study hardware roles
Network Types and Topologies
PAN, LAN, WAN, client/server, peer-to-peer, and topology choice using star, bus and ring scenarios.
Compare network designs
Transmission and Protocols
Choose between fibre, Ethernet, Wi-Fi, Bluetooth, cellular and satellite. Separate media from protocols.
Practise protocol choices
Security and Malware
Authentication, encryption, firewalls, backups, viruses, worms, trojans, spyware, ransomware and phishing.
Match threats to controls
Common network mistakes: treating routers and switches as the same device, confusing transmission media with protocols, and saying one security measure solves every threat.