Your journey to excellence inComputer Science
By Revision Genie
What an Algorithm Is (Step-by-Step Instructions)
Questions are written as you practise.
Algorithm vs Program (Same Idea, Different Thing)
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Decomposition: Breaking a Problem into Sub-Problems
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Abstraction: Removing Unnecessary Detail
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A Systematic Approach to Solving Problems
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Writing Algorithms in Pseudocode
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Representing Algorithms with Flowcharts
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Representing Algorithms with Program Code
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Inputs, Processes and Outputs in an Algorithm
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Spotting Inputs, Processes and Outputs in Given Pseudocode
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Tracing an Algorithm with a Trace Table
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Determining What a Simple Algorithm Does (Purpose)
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Why Different Algorithms Can Solve the Same Problem
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Comparing Algorithms by Time Efficiency (Faster vs Slower)
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Linear Search: How It Works (Mechanics)
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Linear Search: Tracing Step-by-Step
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Binary Search: Why the Data Must Be Sorted
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Binary Search: How It Works (Mechanics)
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Binary Search: Tracing Step-by-Step
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Linear vs Binary Search: Advantages and Disadvantages
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Merge Sort: Splitting a List into Halves
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Merge Sort: Merging Two Sorted Lists
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Merge Sort: Tracing a Full Example
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Bubble Sort: Swapping Adjacent Items
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Bubble Sort: Passes, Comparisons and Swaps
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Bubble Sort: Tracing a Full Example
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Merge Sort vs Bubble Sort: Advantages and Disadvantages
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Integer, Real and Boolean Data Types
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Character and String Data Types
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Choosing the Right Data Type for a Variable
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Variables and Assignment (Storing and Updating Values)
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Constants and Why They’re Useful
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Meaningful Identifier Names (Readable Code)
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Sequence: Running Statements in Order
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Selection: IF, ELSEIF, ELSE Decisions
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Nested Selection (IF Inside IF)
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Count-Controlled Iteration (FOR Loops)
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Condition-Controlled Iteration (WHILE / REPEAT UNTIL)
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Avoiding Infinite Loops (Correct Conditions)
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Arithmetic Operators: +, -, *, /, DIV, MOD
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Order of Operations in Expressions
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Relational Operators: =, ≠, <, >, ≤, ≥
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Building Conditions with Relational Operators
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Boolean Operators: AND, OR, NOT
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Combining Boolean Conditions (With Brackets)
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One-Dimensional Arrays: Indexes and Bounds
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Iterating Through a 1D Array
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Two-Dimensional Arrays: Rows, Columns and Indexes
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Iterating Through a 2D Array (Nested Loops)
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Records: Fields Inside a Single Data Item
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Arrays of Records (Lists of Structured Items)
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Input from a User (Keyboard / Form Input)
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Output to a User (Screen / Console Output)
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String Length and String Indexing
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Substrings and String Slicing
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Concatenating Strings
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Converting Between Characters and Character Codes
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Random Number Generation (Range and Use Cases)
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Using Randomness in Algorithms (Games / Sampling)
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Subroutines: Why We Use Them (Decomposition in Code)
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Procedures vs Functions (Return Values)
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Passing Parameters into a Subroutine
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Using Return Values from Functions
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Local vs Global Variables (Scope Basics)
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Data Validation: Presence, Length and Range Checks
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Data Validation: Format Checks (e.g. Type/Pattern)
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Authentication: Usernames, Passwords and Access
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CAPTCHA: Why It’s Used and What It Stops
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Common Programming Errors: Syntax vs Logic
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Testing Strategies: Normal, Boundary and Erroneous Test Data
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Debugging: Finding and Fixing Errors from Test Results
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Decimal, Binary and Hexadecimal Bases
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Why Computers Use Binary
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Bit Patterns: Same Bits, Different Meanings (Text/Image/Sound/Number)
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Why Hexadecimal Is Useful in Computing
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Binary Place Value (8-bit Numbers 0–255)
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Writing Decimal Numbers (0–255) in Binary
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Hex Place Value and Hex Digits (0–F)
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Writing Decimal Numbers (0–255) in Hex
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Converting Binary to Decimal
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Converting Decimal to Binary
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Converting Binary to Hex (Nibble Grouping)
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Converting Hex to Binary (Nibble Expansion)
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Converting Decimal to Hex
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Converting Hex to Decimal
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Bits and Bytes (b vs B)
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Decimal Prefixes: kB, MB, GB, TB (Powers of 10)
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Comparing File Sizes Using Prefixes
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Adding Two Binary Numbers (With Carry)
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Adding Three Binary Numbers (Column Rules)
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Logical Shifts Left and Right (8-bit)
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Using Shifts for Multiply/Divide by Powers of 2
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What a Character Set Is
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7-bit ASCII: Using an Encoding Table
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Unicode: Why It Exists and Its Advantages over ASCII
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Converting Characters to Codes (Using a Given Table)
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Converting Codes to Characters (Using a Given Table)
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Pixels and How a Bitmap Image Is Stored
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Image Resolution and Colour Depth
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Calculating Image File Size (Resolution × Colour Depth)
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How Changing Resolution Affects Image Quality and File Size
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How Changing Colour Depth Affects Image Quality and File Size
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Sampling Sound: From Analogue to Digital
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Sampling Rate and Sample Resolution (Bit Depth)
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How Sampling Choices Affect Sound Quality
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Calculating Sound File Size (Rate × Resolution × Time)
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Why Data Compression Is Used
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Lossy vs Lossless Compression (What Changes, What Doesn’t)
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Run-Length Encoding: Creating Compressed Data
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Run-Length Encoding: Decompressing Back to Original
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Huffman Coding: Frequency Tables and Idea
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Huffman Coding: Building/Using a Huffman Tree
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Huffman Coding: Calculating Bits Saved
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Hardware vs Software (What Each Means)
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How Hardware and Software Work Together
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Boolean Values: True/False as 1/0
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The NOT Gate: Truth Table and Meaning
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The AND Gate: Truth Table and Meaning
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The OR Gate: Truth Table and Meaning
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The XOR Gate: Truth Table and Meaning
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Logic Gates with Three Inputs (Truth Tables)
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Drawing Logic Circuits Using Gate Symbols
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Reading a Logic Circuit to Produce a Truth Table
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Combining Logic Gates into Larger Circuits
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Boolean Expressions from Logic Circuits
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Logic Circuits from Boolean Expressions
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System Software vs Application Software
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The Purpose of an Operating System
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OS Management: Memory, Processor, Devices and Users
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Utility Software: What It Is and Examples
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Low-Level vs High-Level Programming Languages
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Machine Code: What It Is and Why It’s Processor-Specific
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Assembly Language: What It Is and Why It’s Used
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Translators: Compiler, Interpreter and Assembler
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Compiler vs Interpreter (Key Differences)
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What Main Memory Does in a Computer System
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CPU Components: ALU, Control Unit and Clock
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Registers and Their Role (No Specific Registers Needed)
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Buses: What They Are and Why They Matter
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The Fetch-Decode-Execute Cycle (Full Cycle)
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What Affects CPU Performance: Clock Speed
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What Affects CPU Performance: Cores and Cache
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RAM vs ROM (Volatile vs Non-Volatile)
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Cache and Registers: Why They Exist
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Main Memory vs Secondary Storage
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Why Secondary Storage Is Needed
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Magnetic Storage: How It Stores Data
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Solid State Storage: How It Stores Data (High Level)
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Magnetic vs Solid State: Pros and Cons
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Cloud Storage: What It Means
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Cloud Storage vs Local Storage: Pros and Cons
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Embedded Systems: What They Are
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Embedded vs Non-Embedded Systems (Examples)
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What a Computer Network Is
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Advantages of Using Networks
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Disadvantages and Risks of Networks
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PAN: What It Is (Bluetooth Only)
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LAN: What It Is (Size and Ownership)
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WAN: What It Is (The Internet as a WAN)
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Wired vs Wireless Networks (Key Differences)
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Wireless vs Wired: Advantages and Disadvantages
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Copper vs Fibre Cabling (When Each Is Appropriate)
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What a Network Protocol Is
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IP: Addressing and Routing (Purpose)
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TCP: Reliable Transmission (Purpose)
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HTTP: How Web Pages Are Transferred (Purpose)
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HTTPS: What Changes Compared to HTTP (Purpose)
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SMTP: Sending Email (Purpose)
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IMAP: Retrieving Email (Purpose)
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Why Network Security Matters
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Authentication on Networks (Users and Permissions)
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Encryption on Networks (Protecting Data in Transit)
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Firewalls: What They Do and How Rules Work
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MAC Address Filtering: Allowing/Blocking Devices
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Layering Security Methods Together (Defence in Depth)
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The TCP/IP 4-Layer Model: Names of the Layers
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Application Layer: What Happens Here
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Transport Layer: What Happens Here
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Internet Layer: What Happens Here
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Link Layer: What Happens Here
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Which Protocols Sit in Which TCP/IP Layer
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What Cyber Security Means
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The Main Purposes of Cyber Security
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Social Engineering: What It Is
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Blagging (Pretexting): How It Works
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Phishing: How It Works (Email/SMS)
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Shouldering (Shoulder Surfing): How It Works
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Protecting Against Social Engineering (Practical Behaviours)
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Malware: What It Is (Umbrella Term)
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Computer Viruses: How They Spread and Harm
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Trojans: Disguised Malware and Its Risks
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Spyware: Monitoring Users and Stealing Data
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Protecting Against Malware (Practical Steps)
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Pharming: Redirecting Traffic to Fake Websites
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Weak/Default Passwords: Why They’re Dangerous
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Misconfigured Access Rights: How They Create Risks
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Removable Media Threats (e.g. Infected USBs)
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Unpatched/Outdated Software: Why It’s a Threat
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Penetration Testing: What It Is Used For
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Pen Testing: Internal Attack Simulation
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Pen Testing: External Attack Simulation
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Biometrics for Security (Especially Mobile Devices)
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Password Systems (Strong Password Practice)
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CAPTCHA and Automated Attack Prevention
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Email Confirmations for Identity Checking
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Automatic Software Updates as Protection
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What a Database Is
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What a Relational Database Is
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Tables, Records and Fields (Core Vocabulary)
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Data Types in Databases (Why They Matter)
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Primary Keys: Unique Identifiers
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Foreign Keys: Linking Tables Together
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Reducing Redundancy and Inconsistency with Relational Design
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SELECT: Choosing Which Fields to Show
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FROM: Choosing Which Table(s) to Use
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WHERE: Filtering Records by a Condition
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ORDER BY: Sorting Results ASC and DESC
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Writing Queries Using Two Tables (Maximum)
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INSERT INTO: Adding a New Record
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UPDATE: Editing Existing Data Safely with WHERE
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DELETE: Deleting Records Safely with WHERE
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What “Ethical Impact” Means in Digital Technology
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What “Legal Impact” Means in Digital Technology
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What “Environmental Impact” Means in Digital Technology
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Privacy: What People Expect and Why It Matters
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Security vs Privacy: The Core Trade-Off (Safety vs Access)
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Evaluating a Scenario: Stakeholders, Benefits and Risks
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Cyber Security Impacts: Protection, Surveillance and Harm
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Mobile Technologies: Location Tracking and Personal Data
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Wireless Networking: Convenience vs Eavesdropping Risks
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Cloud Storage: Data Ownership, Access and Jurisdiction Issues
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Cloud Storage: Reliability, Outages and Dependency Risks
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Hacking (Unauthorised Access): Harm, Motivations and Consequences
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Wearable Tech: Health Data, Consent and Data Sharing
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Computer-Based Implants: Safety, Consent and Data Security
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Autonomous Vehicles: Safety, Liability and Decision-Making Ethics
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Environmental Costs: Energy Use of Devices and Data Centres
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Environmental Costs: E-waste and Product Lifecycles
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Key UK Digital Laws (Overview: Data, Access, Copyright, Info Rights)
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Designing a Program to Meet a Brief
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Writing a Program in a Text-Based High-Level Language
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Testing a Program Systematically
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Refining a Program Based on Test Evidence
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Using Programming Tasks to Build Exam-Ready Skills
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What the Practical Programming Statement Confirms (Opportunity to Practise)
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Avoiding Malpractice in Practical Programming Evidence
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