WJEC GCSE Computer Science (Wales): complete guide to the units, the theory and the exams
A complete guide to WJEC GCSE Computer Science (specification 3500) for Wales. Covers the three units, the Unit 1 theory (data representation, hardware, software, networks, security, data organisation, algorithms and impacts), the on-screen Unit 2 programming exam and the Unit 3 software development project, the assessment objectives, and how to revise each area.
WJEC GCSE Computer Science (specification 3500) is the Computer Science GCSE approved by Qualifications Wales for schools in Wales, assessed by three units: a written theory exam, an on-screen programming exam and a software development project. This page is the index: below is a map of the three units, the Unit 1 theory areas, the exam structure, the assessment objectives, and how to study each area, with a direct link to every dot point.
The three units
The qualification has three units. Unit 1 is the written theory exam; Unit 2 is practical programming on screen; Unit 3 is a software development project.
- Unit 1: Understanding Computer Science
- The theory: data representation and data types, hardware and the CPU, software and operating systems, networks and the internet, cyber security, the organisation of data and databases, algorithms and programming principles, logical operations, software engineering, and the ethical, legal and environmental impacts of digital technology.
- Unit 2: Computational Thinking and Programming
- An on-screen examination in which candidates write, test and refine programs and algorithms, applying computational thinking and the programming principles practically.
- Unit 3: Software Development Project
- A non-exam assessment in which candidates analyse, design, develop, test and evaluate a solution to a given task, following the software development life cycle.
Exam structure
WJEC GCSE Computer Science is assessed by two examinations and one non-exam assessment.
- Unit 1 (Understanding Computer Science): written examination, 1 hour 45 minutes, 100 marks, 50 percent.
- Unit 2 (Computational Thinking and Programming): on-screen examination, 2 hours, 60 marks, 30 percent.
- Unit 3 (Software Development Project): non-exam assessment, 20 percent.
Unit 1 mixes short and structured questions with longer, applied and evaluative questions across the whole theory content. Unit 2 is practical, requiring real programming at a computer. Unit 3 rewards a clear, documented, working solution and good development practice.
Assessment objectives
The same three assessment objectives apply across the qualification.
| Assessment objective | What it rewards |
|---|---|
| AO1 | Demonstrate knowledge and understanding of computer science |
| AO2 | Apply knowledge and understanding, including to design, write, test and refine programs |
| AO3 | Make reasoned judgements and evaluate solutions, systems and impacts |
A large share of the marks rewards AO2 (application, including programming), so practising real programming and applying theory to problems matters as much as recalling facts.
How to study WJEC Computer Science
Computer science rewards precise knowledge, accurate calculation and real programming practice.
- Work from the specification statements. Each statement is a checklist; questions are written from them.
- Master the calculations. Binary, hexadecimal and image and sound file-size sums appear every year, so drill them until automatic.
- Learn definitions precisely. Many marks come from clear, distinct definitions (for example switch versus router, validation versus verification).
- Practise the algorithms. Be able to trace and reproduce linear and binary search, bubble and merge sort, and truth tables.
- Programme for real. Units 2 and 3 need hands-on coding, so write, test and refine programs and follow the development life cycle.
- Finish with past papers. Sit WJEC past papers under timed conditions to build speed and exam technique.
Syllabus, dot point by dot point
Each area has specification-statement-level answer pages with worked exam questions and cross-links, plus an overview guide and quiz. Browse the full set at /wjec-gcse/computer-science/syllabus.
Data representation
- Binary and the denary system
- Hexadecimal
- Binary arithmetic and overflow
- Representing negative numbers
- Characters, ASCII and Unicode
- Representing images
- Representing sound
- Compression
Computer systems and hardware
- The CPU and von Neumann architecture
- The fetch-decode-execute cycle
- Processor performance
- Memory: RAM, ROM and virtual memory
- Secondary storage
- Input and output devices
Software and operating systems
Computer networks and the internet
- Networks and topologies
- Network hardware and transmission
- Protocols and layers
- IP addresses and routing
Cyber security
Data organisation and databases
Algorithms and programming principles
- Computational thinking and algorithms
- Searching algorithms
- Sorting algorithms
- Programming constructs
- Subprograms and program structure
- Logical operations
Software development and impacts
- The software development life cycle
- Legislation and ethics
- Environmental and social impacts
- Units 2 and 3 practical overview
For the official specification
WJEC publishes the full specification (3500), past papers and mark schemes at wjec.co.uk. Always revise from the current specification and WJEC's own past papers, because question style is board-specific.
Computer Science guides
In-depth written guides with paired practice quizzes.
- WJEC GCSE Computer Science Algorithms and programming principles: a complete overview of computational thinking, searching, sorting, constructs and logic
A deep-dive WJEC GCSE Computer Science guide to the Algorithms and programming principles content in Unit 1. Covers computational thinking, algorithms in flowcharts and pseudocode, linear and binary search, bubble and merge sort, the three programming constructs, variables and constants, operators, subprograms and a modular approach, and Boolean logic with truth tables and gates.
14 min readRead β - WJEC GCSE Computer Science Computer networks and the internet: a complete overview of networks, hardware, protocols and addressing
A deep-dive WJEC GCSE Computer Science guide to the Computer networks and the internet content in Unit 1. Covers networks and their benefits, LANs and WANs, client-server and peer-to-peer models, topologies, network hardware, wired versus wireless, bandwidth, packets, protocols (TCP/IP, HTTP/HTTPS, FTP, SMTP), layering, IP and MAC addresses, DNS and routing, with the exam patterns WJEC repeats.
13 min readRead β - WJEC GCSE Computer Science Computer systems and hardware: a complete overview of the CPU, the fetch-decode-execute cycle, memory and storage
A deep-dive WJEC GCSE Computer Science guide to the Computer systems and hardware content in Unit 1. Covers the CPU and its components, the von Neumann architecture, the fetch-decode-execute cycle and its registers, factors affecting processor performance, RAM, ROM and virtual memory, secondary storage types, and input and output devices, with the exam patterns WJEC repeats.
13 min readRead β - WJEC GCSE Computer Science Cyber security: a complete overview of threats and how to protect systems and networks
A deep-dive WJEC GCSE Computer Science guide to the Cyber security content in Unit 1. Covers the main threats (malware, phishing, social engineering, brute-force, denial-of-service, SQL injection and interception) and the methods used to protect systems and networks (firewalls, encryption, authentication, anti-malware, penetration testing and policies), with the exam patterns WJEC repeats.
11 min readRead β - WJEC GCSE Computer Science Data organisation and databases: a complete overview of data types, structures, databases and data integrity
A deep-dive WJEC GCSE Computer Science guide to the Data organisation and databases content in Unit 1. Covers the common data types, data structures such as arrays and records, validation and verification, databases and their key terms, flat-file versus relational databases, distributed systems, and data security and integrity, with the exam patterns WJEC repeats.
12 min readRead β - WJEC GCSE Computer Science Data representation: a complete overview of binary, hexadecimal, negative numbers, characters, images, sound and compression
A deep-dive WJEC GCSE Computer Science guide to the Data representation content in Unit 1. Covers binary and denary, hexadecimal, binary arithmetic and overflow, arithmetic shifts, signed numbers in sign and magnitude and two's complement, character sets, bitmap images, sampled sound, file-size calculations and compression, with the conversions and exam patterns WJEC repeats.
14 min readRead β - WJEC GCSE Computer Science Software and operating systems: a complete overview of system and application software, the OS, utilities and translators
A deep-dive WJEC GCSE Computer Science guide to the Software and operating systems content in Unit 1. Covers the difference between system and application software, the operating system and its functions, utility software, and low-level versus high-level languages with assemblers, compilers and interpreters, including the exam patterns WJEC repeats.
12 min readRead β - WJEC GCSE Computer Science Software development and impacts: a complete overview of the life cycle, legislation, ethics and the practical units
A deep-dive WJEC GCSE Computer Science guide to the Software development and impacts content. Covers the software development life cycle and testing, the main legislation (data protection, the Computer Misuse Act and copyright), ethical and cultural issues, the environmental and social impacts of digital technology including e-commerce, and an overview of the practical Units 2 and 3.
12 min readRead β
Computer Science practice quizzes
Multiple-choice drills with worked answer explanations. Your scores stay on this device.
- WJEC GCSE Computer Science Algorithms and programming principles overview quiz16 questionsStart β
- WJEC GCSE Computer Science Computer networks and the internet overview quiz16 questionsStart β
- WJEC GCSE Computer Science Computer systems and hardware overview quiz16 questionsStart β
- WJEC GCSE Computer Science Cyber security overview quiz16 questionsStart β
- WJEC GCSE Computer Science Data organisation and databases overview quiz16 questionsStart β
- WJEC GCSE Computer Science Data representation overview quiz17 questionsStart β
- WJEC GCSE Computer Science Software and operating systems overview quiz16 questionsStart β
- WJEC GCSE Computer Science Software development and impacts overview quiz16 questionsStart β
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