Computer Science simulations
65 interactive Computer Science simulations for ages 11–18, grouped by topic.
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Data representation in bits – numbers, text, images, sound
Computer Science · Data & Binary
Four familiar data types are all reduced to a bit sequence. Type an integer to see its binary form and the number of...
Ages 15–16
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Pixels and RGB color – color depth, file size and RLE compression
Computer Science · Data & Binary
Three workspaces for bitmap images. Paint on a pixel grid, read the bit code of each pixel and see how much...
Ages 15–16
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Binary numbers – bits, bytes, and representing information
Computer Science · Data & Binary
A clickable sequence of 0/1 bits: each bit corresponds to a power of 2, and the decimal number is the sum of the...
Ages 11–12
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Character encoding – Unicode, ASCII and UTF-8
Computer Science · Data & Binary
Type a line of text to see that every character has a Unicode code point, which UTF-8 stores as 1 to 4 bytes. Tap a...
Ages 15–16
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Fetch–Decode–Execute Cycle – Inside a Simple CPU
Computer Science · Computers & Hardware
A tiny CPU with PC, MAR, MDR, CIR, ACC, ALU and a control unit, connected to 16 or 32 memory cells by the address,...
Ages 16–17
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CPU performance – clock speed, cores, cache and system on a chip
Computer Science · Computers & Hardware
Set the clock speed, the number of cores and the L2 cache size, then run five kinds of task to see how long each...
Ages 16–17
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CPU scheduling and deadlock – FCFS, SJF, round robin and priority
Computer Science · Computers & Hardware
Enter processes with arrival times, burst times and priorities, choose FCFS, SJF, SRTF, round robin (set the time...
Ages 16–17
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Hardware, software and the path of data
Computer Science · Computers & Hardware
A block diagram of a computer with an input device, a CPU (control unit and arithmetic-logic unit), main memory...
Ages 12–13
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Operating system memory management – RAM, paging, virtual memory and OS functions
Computer Science · Computers & Hardware
Open and close programs and watch RAM fill up page by page. When RAM is full, the operating system moves little-used...
Ages 16–17
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Computer generations – tracing Moore's law
Computer Science · Computers & Hardware
Four computer generations sit on one 1945–2025 timeline with a representative machine for each: ENIAC, the IBM 1401,...
Ages 13–14
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Parallel and distributed computing – Amdahl's law, GPUs and pipelining
Computer Science · Computers & Hardware
Split a job into tasks with a parallel fraction p, then run it sequentially on one core, in parallel on n cores, or...
Ages 16–17
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Manual work or computer automation?
Computer Science · Computers & Hardware
A familiar task (grading papers, library loans, or store checkout) is modeled through the time each item takes, its...
Ages 14–15
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Network Topologies – Star, Bus, Ring and Mesh
Computer Science · Networks & the Internet
Build a network of 4–8 computers as a star, bus, ring, full mesh or partial mesh and send packets between them. Cut...
Ages 17–18
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Domain names, DNS and IP addressing – subnet masks and routing
Computer Science · Networks & the Internet
Type a domain name and a DNS server looks it up in a table to return the matching IP address. The program then ANDs...
Ages 15–16
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Network Packets – from Computer A to Computer B through Routers
Computer Science · Networks & the Internet
The message is split into numbered packets, and each one finds its own way through the routers to the receiving...
Ages 11–12
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Client–server model: HTTP requests, caching, queues, peer-to-peer and GET vs POST
Computer Science · Networks & the Internet
Many clients keep sending HTTP requests to one server. A request that hits the cache is answered instantly, while...
Ages 17–18
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TCP/IP layers – encapsulation, MAC and IP addresses, TCP vs UDP
Computer Science · Networks & the Internet
Follow data from an application (HTTP, HTTPS, SMTP, POP3, IMAP, FTP, DNS or a video call) as it is wrapped layer by...
Ages 17–18
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Network hardware and transmission media – build a LAN and connect it to the Internet
Computer Science · Networks & the Internet
Build a LAN with network interface cards (NICs), a switch, a router, a wireless access point and a modem that...
Ages 17–18
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Translators – compiler, interpreter and assembler
Computer Science · Algorithms & Problem Solving
The same short program is translated by a compiler, which checks the whole program, lists every syntax error and...
Ages 15–16
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Code Stepper – Variables, Data Types and Expressions
Computer Science · Algorithms & Problem Solving
Step through a short Python or exam-style pseudocode program one line at a time. A variables table shows how each...
Ages 15–16
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Binary search trees – insert, search, delete and tree traversals
Computer Science · Algorithms & Problem Solving
Insert, search for and delete keys in a binary search tree and watch the comparison path through each node, the tree...
Ages 17–18
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Recursion – call stack and call tree
Computer Science · Algorithms & Problem Solving
Step through recursive functions – factorial, Fibonacci, sum of a list, binary search, the disk-moving tower puzzle...
Ages 17–18
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Functions and the call stack – parameters, return values and scope
Computer Science · Algorithms & Problem Solving
Step through programs that call procedures and functions and watch each call push a stack frame: arguments bound to...
Ages 15–16
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Testing lab – test data, error types and data validation
Computer Science · Algorithms & Problem Solving
Three hands-on activities about testing programs. Design normal, boundary, extreme and erroneous test data for a...
Ages 13–14
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Classes and objects – references, encapsulation and inheritance
Computer Science · Algorithms & Problem Solving
Step through small Python or Java programs that define classes, create objects and call methods, and watch a memory...
Ages 17–18
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Arrays and lists – index, insert, remove and traverse
Computer Science · Algorithms & Problem Solving
A list is shown as indexed cells with a pointer. Students read, write, append, insert and remove elements and watch...
Ages 15–16
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Finite state machines – traffic lights, DFAs, NFAs and regular languages
Computer Science · Algorithms & Problem Solving
Step preset state machines (traffic light, vending machine, turnstile) through a sequence of events and watch the...
Ages 15–16
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Stacks, queues and linked lists – pointers step by step
Computer Science · Algorithms & Problem Solving
Push and pop on a stack, enqueue and dequeue on linear, circular and priority queues, and insert, delete and search...
Ages 17–18
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Visual sorting: bubble, selection, insertion and merge sort step by step
Computer Science · Algorithms & Problem Solving
A sequence of numbers is drawn as bars; choose bubble sort, selection sort, insertion sort or merge sort, then press...
Ages 13–14
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Flowchart and trace table – selection and iteration
Computer Science · Algorithms & Problem Solving
The same algorithm is shown side by side as a flowchart and as pseudocode, Python or blocks. Students set the inputs...
Ages 13–14
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String tracer – indices, substrings and string algorithms
Computer Science · Algorithms & Problem Solving
A string is drawn as a row of character cells indexed from 0. String operations mode covers concatenation, length,...
Ages 15–16
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Algorithm complexity – O(log n), O(n), O(n log n), O(n²) and a sorting race
Computer Science · Algorithms & Problem Solving
A chart plots the number of steps against input size n for the functions log₂n, n, n·log₂n and n², alongside...
Ages 15–16
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Maze pathfinding – BFS, DFS and A*
Computer Science · Algorithms & Problem Solving
A grid with walls, a start cell and a goal cell. Students choose breadth-first search (BFS, using a queue),...
Ages 17–18
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Linear search vs. binary search – counting comparisons
Computer Science · Algorithms & Problem Solving
The same array and the same target value run through linear search (scanning from the start) and binary search...
Ages 12–13
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Community Towers of Hanoi
Computer Science · Algorithms & Problem Solving
Learn recursion by solving the Towers of Hanoi. Watch the call stack grow and shrink automatically, or try to solve...
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Decision tree classifier – sorting data with yes/no questions
Computer Science · Data, AI & Machine Learning
Two-class data on a plane defined by two features (weather and going outside, apple or lemon, passing a test). The...
Ages 17–18
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Big Data and Recommender Systems – Filter Bubbles
Computer Science · Data, AI & Machine Learning
The top half shows the big data pipeline: raw records are collected, then cleaned (removing duplicates, missing...
Ages 17–18
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k-nearest neighbours (k-NN) classification: an idea from machine learning
Computer Science · Data, AI & Machine Learning
The training data is two classes of points on a plane defined by two features. Students drag a new point (the star)...
Ages 17–18
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Machine learning from data: more samples, better accuracy
Computer Science · Data, AI & Machine Learning
A simple classifier learns from labeled samples: it computes the centroid of each class, then uses the perpendicular...
Ages 16–17
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Directory tree – paths and file search
Computer Science · Files, Storage & Databases
A directory tree you can click to expand, collapse, and select, just like File Explorer. Students pick a file to...
Ages 11–12
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Database normalisation – from a flat table to 3NF, with ER diagrams
Computer Science · Files, Storage & Databases
Start from a flat table full of repeated data, trigger update, insert and delete anomalies, then step through 1NF,...
Ages 16–17
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Relational databases and queries
Computer Science · Files, Storage & Databases
Two tables, STUDENTS and CLASSES, are linked by the foreign key ClassID pointing to the primary key ClassID of the...
Ages 16–17
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File Storage – local disk, server or the cloud
Computer Science · Files, Storage & Databases
The same file is kept in three places: a personal computer's disk, a school server, or a cloud storage service....
Ages 16–17
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Data compression and multi-copy backup
Computer Science · Files, Storage & Databases
A file is compressed three ways: kept as is, compressed losslessly (ZIP, PNG, FLAC), and compressed with loss (JPEG,...
Ages 17–18
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Secondary storage – magnetic, optical and solid-state devices compared
Computer Science · Files, Storage & Databases
Look inside three kinds of storage: a hard disk drive (spinning platters, magnetised regions, read/write head, seek...
Ages 16–17
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How search engines rank results
Computer Science · Files, Storage & Databases
A small collection of twelve web pages with different titles, URLs, publish dates and trust levels. Students type a...
Ages 14–15
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Spreadsheet formulas – functions and copying cell references
Computer Science · Digital Applications
A small working spreadsheet: click a cell to select it, type a number or a formula starting with = into the formula...
Ages 12–13
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From spreadsheet table to chart
Computer Science · Digital Applications
The data table can be edited right on the page: change a number and the chart beside it redraws instantly. Students...
Ages 13–14
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Editing video on a timeline
Computer Science · Digital Applications
A video-editing timeline with several scenes: students click to select a scene, drag its right edge to trim it,...
Ages 14–15
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Vector and bitmap graphics – zooming into resolution and file size
Computer Science · Digital Applications
The same drawing is built two ways: a vector image stores each shape's formula, so it redraws crisply at any zoom...
Ages 15–16
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Usability and accessibility testing – simulated users and WCAG
Computer Science · Digital Applications
Simulated users with different needs (a typical user, an older user with low vision, a user with a hand tremor, a...
Ages 17–18
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Mind maps: building, editing and switching views
Computer Science · Digital Applications
A mind map drawn on canvas: the main topic sits at the centre, level-1 branches spread out evenly around it, and...
Ages 12–13
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Word processing – text formatting
Computer Science · Digital Applications
A sample document loads with the tools ready. Students click a paragraph to select it, then click formatting buttons...
Ages 11–12
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HTML and CSS playground – content, structure and style
Computer Science · Digital Applications
Edit the content, the HTML markup and a CSS stylesheet in separate panes and watch the rendered page and the DOM...
Ages 17–18
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Digital image processing: pixels, filters and compression
Computer Science · Digital Applications
An image is generated right on the page and then re-digitized at the resolution you choose, shown next to the...
Ages 17–18
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Digital footprint and privacy – app permissions, cookies and privacy settings
Computer Science · Digital Safety & Ethics
Try Zibbo, a fictional photo-sharing app: grant location, contacts, camera and microphone permissions, accept or...
Ages 14–15
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Malware spreading in a network – testing cyber defences
Computer Science · Digital Safety & Ethics
A school computer network has several rooms and a file server. Malware gets in through e-mail attachments, USB...
Ages 15–16
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Encryption and code-breaking – from the Caesar cipher to 128-bit keys
Computer Science · Digital Safety & Ethics
Turn a Caesar cipher wheel to encrypt and decrypt with a shift k, then break secret messages with frequency analysis...
Ages 15–16
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Password strength and phishing messages
Computer Science · Digital Safety & Ethics
Type a password and the program counts the character sets used (lowercase, uppercase, digits, symbols), then...
Ages 11–12
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Spotting fake news and how fast it spreads
Computer Science · Digital Safety & Ethics
A news post appears on screen the way it would on social media. Students click through verification steps (source,...
Ages 14–15
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Firewalls and access control – packet-filter rules and least privilege
Computer Science · Digital Safety & Ethics
Write rules for a packet-filter firewall (allow or deny by direction, protocol, source IP address and destination...
Ages 15–16
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IT careers – learning pathway
Computer Science · Careers in Computing
Each IT career track is described as a list of skills, and each skill needs a set number of practice hours. Students...
Ages 16–17
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Matching abilities to IT career tracks
Computer Science · Careers in Computing
Students rate five abilities on sliders: logical thinking, working with data, communication and teamwork, artistic...
Ages 13–14
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Tech team roles – who does what in an IT project
Computer Science · Careers in Computing
A tech team takes on a project (a school app, a school library website or a computer lab upgrade) with seven tasks...
Ages 16–17
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Agile software sprint – plan, build, test, release
Computer Science · Careers in Computing
A small software team runs an Agile sprint to build a school club app: pick user stories from the backlog that fit...
Ages 17–18
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