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KS3 Computing · Engineer

Year 8

Inside the machine: the CPU, memory and software. Building web pages, number systems and text, your first Python, and the classic searching and sorting algorithms.

Units, term by term

One unit each half term. Open a lesson to study it, try it and check yourself.

Autumn 1

Computer Systems

Input, process, output, storage; the CPU and the fetch–decode–execute cycle; RAM, ROM and secondary storage; logic gates; system and application software.

What you will know by the end
  • Von Neumann: one memory holds both data and instructions; the CPU fetches, decodes, executes.
  • Registers, ALU, control unit, buses: what each one does.
  • RAM is working memory and volatile; ROM holds the start-up code; storage keeps files.
  • AND, OR, NOT and their truth tables; two gates make a circuit.
  • The operating system manages hardware and runs applications; utilities keep the system healthy.
Syllabus and key words
  • Topic 8: Inside the computer
    • Name the parts of the CPU in the von Neumann design, and say what each of the three buses carries.
    • Step through fetch–decode–execute, saying what the PC, MAR, MDR, CIR and ACC hold at each moment.
    • Work out how long one clock tick lasts, and explain why more cores or more cache isn't always faster.
    • Compare RAM, ROM, virtual memory and the three kinds of storage (magnetic, optical, solid state), and choose storage for a job.
    • Explain what an embedded system is, and spot them around you.
  • Topic 10: Software
    • Sort software into system and application, and draw the layers from hardware up to the user.
    • Explain the six jobs of an operating system, including how it shares the CPU (round robin).
    • Pick the right utility for a problem: defragmenter, compression, backup, encryption, antivirus.
    • Compare open source and proprietary software, and high-level and low-level languages.
    • Say what a compiler, an interpreter and an assembler do, and what an IDE gives you.
  • Topic 9: Logic gates
    • Know the rules for NOT, AND, OR and XOR, and draw their symbols.
    • Write a full truth table for any circuit, with no missing rows.
    • Turn a circuit into an expression, and an expression into a circuit, in AQA or OCR notation.
    • Explain how a half adder uses XOR and AND to add two bits.
    • Link gates to real chips, transistors and and / or / not in Python.
  • Topic 1: What a computer is
    • Sort any device into input, process, output or storage, and follow one real example through all four.
    • Explain why computers use electricity, and why they use only two states (0 and 1), not ten.
    • Describe a transistor as a switch, and show how two switches can make a decision.
    • Tell hardware from software, and embedded computers from general-purpose ones.
    • Explain the stored-program idea, place the big inventions on a timeline, and say why an LED needs a resistor.
CPU
Central Processing Unit: the processor that runs instructions.
Register
Tiny storage inside the CPU, like the PC or ACC.
Bus
A set of wires that carries addresses, data or control signals between parts of the computer.
RAM
Random Access Memory: fast, volatile working memory.
Volatile
Loses its contents when the power goes off.
Cache
Small, very fast memory on the CPU chip.
Clock speed
How many cycles a CPU does per second, in GHz.
Embedded system
A small computer built into a device for one job.
Software
Programs: instructions that tell hardware what to do.
Operating system
System software that manages hardware and runs programs.
Driver
Small program that lets the operating system talk to a device.
Open source
Software whose code anyone can see, change and share.
Machine code
Binary instructions the CPU actually runs.
Compiler
Translates a whole program into machine code before it runs.
Interpreter
Translates and runs code one line at a time.
IDE
Integrated Development Environment: the program you code in.
Boolean
A value that is only True or False.
Logic gate
A tiny circuit that takes bits in and gives one bit out by a fixed rule.
Truth table
Lists every input combination and its output.
Boolean expression
A rule written with AND, OR and NOT that gives True or False, like A AND NOT B.
Half adder
An XOR gate plus an AND gate: adds two bits.
Transistor
An electronic switch with no moving parts.
Input / output
Anything that gets information into the computer. Keyboard, mouse, touchscreen, microphone, camera, a temperature sensor.
Process
The computer follows instructions to change that information. Add two numbers. Move a character. Sort a list. The CPU does this.
Hardware
The physical parts of a computer.
  1. Input, process, output, storageTheory
  2. The CPU and the fetch–decode–execute cycleTheory
  3. RAM, ROM and secondary storageTheory
  4. Logic gates AND, OR, NOT and truth tablesUnplugged
  5. Operating systems, applications and utilitiesTheory

End-of-unit challenge: Label and explain a system diagram, then solve three logic-circuit puzzles.

Homework: Study pages 8 and 9 to the quiz.

Extra challenge: Find the RAM, storage and CPU speed of a computer at home.

Arcade: this unitPC Build Bench
Autumn 2

Building the Web

HTML structure, text, links and images, CSS for colour, fonts and layout, how search engines find pages, and a one-page wiki about a favourite game.

What you will know by the end
  • HTML labels what things are; CSS says how they look.
  • head and body; h1, p, a, img, ul; attributes like href and src.
  • A CSS rule: selector, property, value. One stylesheet, many pages.
  • Client asks, server answers: HTTP. HTTPS adds the padlock.
  • Search engines crawl, index, rank. Alt text helps people and crawlers.
Syllabus and key words
  • Topic 16: The web
    • Explain why the web and the internet are not the same thing, and take any URL apart.
    • Follow one HTTP request from Enter to a drawn page, and read status codes like 200, 301, 404 and 500.
    • Read and write HTML elements and attributes, see the page as a tree (the DOM), and style it with CSS and the box model.
    • Explain HTTPS, hosting, domain names (.es and .co.uk), how search engines crawl, index and rank, and why accessibility and cookies matter.
  • Topic 15: Networks and the internet
    • Say why we connect computers, and tell a LAN from a WAN, and the internet from the web.
    • Name the hardware in a home or school network and say what each box does.
    • Explain IP and MAC addresses, and why an IPv4 part stops at 255.
    • Follow a DNS lookup and a packet's journey, step by step.
    • Use protocols, layers, bandwidth and latency correctly, and work out download times by hand.
URL
The full web address of something online.
Protocol
A set of agreed rules for communication.
HTML
Markup language for the content of web pages.
CSS
Language that styles how web pages look.
LAN / WAN
Local Area Network: a network over a small area.
Router
Connects different networks and forwards packets.
IP address
A device's address on a network. IPv4 = 4 bytes.
MAC address
Fixed unique ID of a network card. 48 bits in hex.
DNS
Domain Name System: turns website names into IP addresses.
Packet
A small numbered chunk of data sent across a network.
Bandwidth / latency
How much data a connection can carry per second.
  1. HTML structure: tags, head and bodyPractical
  2. Text, links and imagesPractical
  3. CSS: colours, fonts and layoutPractical
  4. Search engines: crawling, indexing and rankingTheory
  5. Build a one-page wiki about a favourite gameProject

End-of-unit challenge: Build a page to a written spec, then explain in three steps how a search engine would find it.

Homework: Study page 16 to the quiz.

Extra challenge: View the source of a real page and find the title tag.

Arcade: this unit
Spring 1

Representations: from clay to silicon

Tally marks to number bases, binary to denary and back, binary addition and overflow, ASCII and Unicode, units and a first look at hex.

What you will know by the end
  • Place value: 128 64 32 16 8 4 2 1. Eight bits hold 0 to 255.
  • Denary to binary: subtract the biggest column that fits.
  • Binary addition: 1 + 1 = 10. Overflow when the answer needs a ninth bit.
  • ASCII: one byte per character; Unicode covers every alphabet and emoji.
  • Hex: one digit is four bits; it is a shorthand for humans.
Syllabus and key words
  • Topic 3: Binary, denary and hex
    • See place value in denary, then use the same idea with 2 digits (binary) and 16 digits (hex).
    • Convert binary ↔ denary ↔ hex by hand, one column at a time.
    • Add in binary, spot overflow, and use shifts to multiply and divide by 2.
    • Bonus: store negative numbers with two's complement.
  • Topic 4: Representing text
    • Explain why every computer must use the same lookup table for characters.
    • Turn characters into ASCII codes and back, using the clever order (A = 65, a = 97, '0' = 48).
    • Work out how much space text takes, and how many bits a character set needs.
    • Say why Unicode exists, and how UTF-8 stores ñ, € or 😀 in 1 to 4 bytes.
  • Topic 2: Bits and bytes
    • Say what a bit is, and why one bit is one yes/no answer.
    • Work out how many patterns n bits make, and the biggest number they hold.
    • Explain why a byte is 8 bits, and climb up and down the units ladder (KB, MB, GB…).
    • Never mix up Mbps (internet speed, bits) and MB (file size, bytes) again.
Denary
Base 10. Our everyday numbers.
Binary
Base 2. Digits 0 and 1. Columns 128 64 32 16 8 4 2 1.
Hexadecimal
Base 16: digits 0–9 then A–F. One digit = 4 bits.
Overflow
A result too big for the bits available.
Character set
The agreed list of characters and the number for each.
ASCII
7-bit character set with 128 characters. A = 65.
Unicode
Character set for every writing system, plus emoji.
UTF-8
The usual way Unicode is stored. 1 byte for the old ASCII characters (so old files still work), 2 bytes for ñ or é, 3 for €, 4 for emoji.
Bit
One binary digit, 0 or 1. One switch.
Byte
8 bits. 256 possible patterns.
Nibble
4 bits. One hex digit.
  1. Tally marks to number basesTheory
  2. Binary to denary and backTheory
  3. Binary addition and overflowTheory
  4. ASCII and UnicodePractical
  5. Units and an introduction to hexadecimalTheory

End-of-unit challenge: A binary escape room: each solved conversion unlocks the next door.

Homework: Study pages 3 and 4; Bit Maths Lab 'Convert' section.

Extra challenge: Write your initials in binary and in hex.

Arcade: this unit
Spring 2

Python I

print, input and sequence; variables, data types and operators; if / elif / else; while loops; for and range; the random module.

What you will know by the end
  • Python runs one line at a time, top to bottom.
  • input() always gives text; int() turns it into a number.
  • = stores; == compares. Say 'becomes'.
  • if / elif / else chooses; while repeats while a condition is true; for counts.
  • A syntax error stops the program; a logic error runs and gives the wrong answer.
Syllabus and key words
  • Topic 13: Programming basics
    • Read a Scratch script and write the same thing in Python.
    • Use variables, the four data types and casting, and spot the input() bug.
    • Work out DIV (//) and MOD (%) by hand, and use MOD to test for even numbers.
    • Trace if / elif / else, for with range() and while loops line by line.
    • Tell syntax, runtime and logic errors apart, and fix each kind.
  • Topic 11: Algorithms
    • Say what makes a set of instructions an algorithm: precise, ordered, finite.
    • Use decomposition, pattern recognition, abstraction and algorithmic thinking on a real problem.
    • Read and write the same algorithm as a flowchart, AQA and OCR pseudocode, and Scratch blocks.
    • Dry-run an algorithm with a trace table, count loop repeats, and spot the bug.
    • Compare two algorithms by counting their steps.
Variable
A named place in memory that holds a value.
Assignment
Storing a value in a variable. = in Python, ← in pseudocode.
Casting
Changing a value from one data type to another, like int("13").
Concatenation
Joining strings together: "7" + "7" = "77".
Selection
Choosing a path with if / else.
Iteration
Repeating steps: a loop.
Boolean
A value that is only True or False.
Infinite loop
A loop whose condition never becomes false.
Algorithm
Precise, ordered, finite steps to solve a problem.
Decomposition
Breaking a problem into smaller ones.
Abstraction
Ignoring detail that doesn't matter for the problem.
Sequence · selection · iteration
Steps one after another. First this, then this.
Pseudocode
Code-like writing for algorithms, without strict rules.
Trace table
Records variable values step by step to check logic.
  1. print, input and sequencePractical
  2. Variables, data types and arithmeticPractical
  3. if / elif / elsePractical
  4. while loopsPractical
  5. for, range and randomPractical

End-of-unit challenge: A number-guessing game with limited lives and a replay option.

Homework: Study page 13 to the quiz.

Extra challenge: A program that tells you if a year is a leap year.

Arcade: this unit
Summer 1

Algorithms: search and sort

Linear versus binary search with cards, bubble sort step by step, insertion and merge sort unplugged, comparing efficiency, and a linear search in Python.

What you will know by the end
  • Linear search checks each item; binary search halves a sorted list each time.
  • Bubble sort: compare neighbours, swap if wrong, repeat until no swaps.
  • Insertion sort builds the sorted part one item at a time; merge sort splits then merges.
  • Efficiency: count the comparisons. n log n beats n² as n grows.
  • Choose the algorithm for the situation: sorted or not, big or small.
Syllabus and key words
  • Topic 12: Searching and sorting
    • Carry out a linear search and a binary search by hand, and say when each one can be used.
    • Work out the most checks a binary search can need, using halving (log₂).
    • Run bubble sort, insertion sort and merge sort by hand, pass by pass.
    • Compare algorithms by counting comparisons, and explain n, n² and n log n in plain words.
  • Topic 11: Algorithms
    • Say what makes a set of instructions an algorithm: precise, ordered, finite.
    • Use decomposition, pattern recognition, abstraction and algorithmic thinking on a real problem.
    • Read and write the same algorithm as a flowchart, AQA and OCR pseudocode, and Scratch blocks.
    • Dry-run an algorithm with a trace table, count loop repeats, and spot the bug.
    • Compare two algorithms by counting their steps.
Linear search
Check every item in turn.
Binary search
Search a sorted list by halving it each step.
Bubble sort
Swap neighbours until a whole pass makes no swaps.
Insertion sort
Slide each item into its place in the sorted part.
Merge sort
Split into single items, then merge back in order.
Algorithm
Precise, ordered, finite steps to solve a problem.
Decomposition
Breaking a problem into smaller ones.
Abstraction
Ignoring detail that doesn't matter for the problem.
Sequence · selection · iteration
Steps one after another. First this, then this.
Pseudocode
Code-like writing for algorithms, without strict rules.
Trace table
Records variable values step by step to check logic.
Variable
A named place in memory that holds a value.
  1. Linear vs binary search with numbered cardsUnplugged
  2. Bubble sort, step by stepUnplugged
  3. Insertion sort and merge sort, unpluggedUnplugged
  4. Comparing efficiency by counting comparisonsTheory
  5. Code a linear search in PythonPractical

End-of-unit challenge: Trace each sort on a short list, then justify which algorithm suits a given scenario.

Homework: Study page 12 to the quiz; practice 'Merge two lists'.

Extra challenge: Time how long it takes to find a word in a dictionary, with and without the alphabet.

Arcade: this unit
Summer 2

Raid: App Forge

A design brief from user needs, App Inventor screens and components, events and logic, then the guild Raid: an app for a problem at school, user-tested and pitched.

What you will know by the end
  • Event-driven: code runs when a button is pressed, not top to bottom.
  • A user interface is components with properties; the logic is blocks.
  • Design from a need: who, what problem, what success looks like.
  • Test with real users; write down what they did, not what you hoped.
Syllabus and key words
  • Topic 14: Programming further
    • Read and change lists (including 2D lists) using indexes that start at 0.
    • Slice strings with s[a:b] and predict the result, every time.
    • Write procedures and functions with parameters and return values, and explain local vs global scope.
    • Make programs robust: validation, authentication, try/except and file handling.
    • Plan tests with normal, boundary and erroneous data.
  • Topic 11: Algorithms
    • Say what makes a set of instructions an algorithm: precise, ordered, finite.
    • Use decomposition, pattern recognition, abstraction and algorithmic thinking on a real problem.
    • Read and write the same algorithm as a flowchart, AQA and OCR pseudocode, and Scratch blocks.
    • Dry-run an algorithm with a trace table, count loop repeats, and spot the bug.
    • Compare two algorithms by counting their steps.
  • Topic 19: Digital life, law and ethics
    • Explain a digital footprint, keep accounts private, and know the steps when something online feels wrong.
    • Spot the red flags in a phishing message, and check whether information online is trustworthy.
    • Name the three UK laws (Computer Misuse Act, Data Protection Act, Copyright Act), what each one covers, and the Spanish equivalents.
    • Choose and read a Creative Commons licence.
    • Argue both sides of an ethical question: AI, surveillance, the digital divide, the environment and wellbeing.
List
One name holding many values in order. Also called an array.
Index
An item's position in a list, counting from 0.
Subroutine
A named block of code you can call when needed.
Function
A subroutine that returns a value.
Parameter
A placeholder in a subroutine for a value passed in.
Validation
Checking input is reasonable before using it.
Boundary data
Test data at the very edge of what's allowed.
Algorithm
Precise, ordered, finite steps to solve a problem.
Decomposition
Breaking a problem into smaller ones.
Abstraction
Ignoring detail that doesn't matter for the problem.
Sequence · selection · iteration
Steps one after another. First this, then this.
Pseudocode
Code-like writing for algorithms, without strict rules.
Trace table
Records variable values step by step to check logic.
Variable
A named place in memory that holds a value.
Digital footprint
The trail of everything you do online.
Phishing
Fake messages that trick people into giving details.
Computer Misuse Act
UK law (1990) that makes hacking and spreading malware crimes.
Data Protection Act
UK law (2018), with UK GDPR, controlling how personal data is used.
Copyright
Automatic legal protection for original creative work.
Open source
Software whose code anyone can see, change and share.
Ethics
AI that is biased because its training data was. Cameras that keep us safe and also watch us. The digital divide: who is left out when everything moves online. Screen time and sleep. Practise arguing both sides.
  1. Writing a design brief from user needsTheory
  2. App Inventor: screens and componentsPractical
  3. Events and logic: buttons, variables and conditionsPractical
  4. Raid build: an app for a problem at schoolProject
  5. Raid build: user testing and improvementsProject

End-of-unit challenge: Annual Raid: a Dragons' Den pitch with a live demo, judged on usefulness, design, code and teamwork.

Homework: Study page 14 steps 1 to 3 (lists and functions, ready for Year 9).

Extra challenge: Sketch the app you wish existed, on paper.

Arcade: this unit

Topics, in teaching order

Year 8 hub: this year's formulas and Tinkercad builds.

Topic 8 · Year 8

Inside the computer

The CPU does the work, RAM holds what it's using now, and storage keeps everything long-term. The CPU repeats one loop: fetch, decode, execute.

Topic 10 · Year 8

Software

System software runs the computer. Application software does jobs for people. Programs must be translated into machine code before they run.

Topic 16 · Year 8

The web

A web page is text written in HTML (what's on the page), styled with CSS (how it looks), sometimes with JavaScript (what it does). Your browser fetches it using a URL.

Topic 3 · Year 8

Binary, denary and hex

Computers store numbers in binary (base 2). We use denary (base 10). Programmers use hex (base 16) as a short way to write binary. All three use place value.

Topic 4 · Year 8

Representing text

Every character gets a number. The number is stored in binary. The agreed list is a character set.

Topic 13 · Year 8

Programming basics

A program stores information in variables, works on it with operators, and controls the order with sequence, selection and iteration. Examples are in Python.

Topic 12 · Year 8

Searching and sorting

Searching finds an item. Sorting puts items in order. Some algorithms are hugely faster than others on big lists.

Revise

Revise

Revise Year 8

A mixed quiz, key-word flashcards and endless practice for this year.

Projects and games

Years 7–9

PC Build Bench

Build a PC on screen part by part, fill a customer's order, then face the Boss Battle.

Years 7–9

Computing Quest Arcade

Games, puzzles and retrieval starters for all 18 KS3 Quest units: phishing spotter, packet puzzle, bot maze, logic gate lab and more.

Years 7–11

Tinkercad Maker Course

How electricity really works, 3D design, circuits that run real code, and a build checker.

Tinkercad · Intermediate · 35 minutes

Letters in lights

8 LEDs show a character's ASCII code: one whole byte, in lights. In blocks you pick the letter's code; in C++ you type letters in the Serial Monitor.

Tinkercad · Intermediate · 30 minutes

Traffic light with a crossing button

A UK-style traffic light that lets people cross when they press a button. It uses sequence, selection, iteration and variables, and the C++ adds a subroutine.

Explainers and study pages

Years 8–11

How the Web Works

Fourteen stops from the URL to a good page: DNS, packets, HTTP, HTTPS, HTML, CSS, JavaScript and more, each with something to try.

Years 8–11

Bit Maths Lab

All the binary maths, one small step at a time and colour-coded. Tap anything; nothing can break.

Years 8–11

Binary, Denary and Hex

Three ways of writing the same numbers. Place value column by column, with every conversion broken down.

Years 8–11

Code in Words

Python, Java, HTML, CSS and C++ explained line by line in plain words, with a step-through runner.

Years 7–9

The Skipped Resistor

Your LED lit up but Tinkercad put a star on it. Why too much current flows, and how to fix it.

Years 7–9

Every topic, step by step

All 19 KS3 topics as one long read: every why answered, every calculation shown line by line.