Computer Science & Digital Technology Teacher
Free, interactive tools for GCSE & A-Level students. No login, no install — just open and learn.
Drag-and-drop WJEC flowchart symbols to design algorithms visually. 5 example algorithms, export as PNG or SVG.
Linear and Binary search step by step. Visual array with pointers, comparison counters, and complexity analysis.
Bubble, Insertion, Selection, Merge and Quick Sort with step-through animation, custom data sets, and Big O analysis.
Build weighted graphs with drag-and-drop, watch Dijkstra's algorithm find the cheapest route step by step.
Interactive growth chart showing how O(1) through O(2ⁿ) scale. Toggle complexities, see operations table.
Race two sorting algorithms head-to-head on identical data. Countdown, live bars, comparison stats, winner declared!
Watch Breadth-First and Depth-First search side by side. See the queue vs stack, visit order, and 3 preset graphs.
Base conversion with full working, binary addition, arithmetic shifts, overflow/underflow.
Calculate file sizes for bitmaps and sound files with step-by-step working. Presets for common scenarios.
Watch RLE and Huffman coding work step by step. Frequency tables, compression ratios, lossy vs lossless explained.
See how sound waves become digital data. Adjust sample rate and bit depth, watch quality change in real-time.
Zoom into bitmap and vector images side by side. See pixels appear vs clean scaling. 5 shapes, colour depth slider.
Type a domain and watch the full DNS resolution process animate — from browser cache to root server to IP address.
Step-by-step visualisations of 6 attack types: phishing, DDoS, MitM, SQL injection, brute force, social engineering. With defences.
Drag-and-drop network builder. Place devices, connect cables, simulate packets. 6 preset topologies with SPOF detection.
Caesar cipher, Vigenère cipher — encrypt messages and see how each letter transforms. Plus symmetric vs asymmetric comparison.
Serial vs parallel, simplex vs duplex, packet switching — watch data travel with animated bits and packets.
Interactive gates with toggle inputs, auto-generated truth tables, and a Boolean expression builder. AND, OR, NOT, XOR, NAND, NOR.
Write LMC assembly, watch the FDE cycle animate, see registers and 100 memory mailboxes update in real time. 5 preset programs.
Watch code transform through lexical analysis, syntax trees, semantic checks, code generation and optimisation — step by step.
Compare FCFS, SJF, Round Robin, Priority scheduling with Gantt charts and turnaround/waiting time metrics.
Watch the Von Neumann architecture in action. FDE cycle with register highlighting, bus labels, RAM view, 3 programs.
Compare magnetic, optical and solid state storage. Interactive stat bars for speed, capacity, cost and durability.
Paste a Python error message, get a student-friendly explanation with causes and fix suggestions. 9 error types covered.
Convert between Python and WJEC-style pseudocode (Appendix B). Bi-directional with full reference table.
Drag scrambled code blocks into the correct order. 10 built-in problems (easy→hard) or create your own from any code.
Turn Python code into beautiful images for slides and worksheets. 8 themes (Monokai, Dracula, Nord...), line numbers, PNG export.
Watch recursive call stacks build and unwind. Factorial, Fibonacci, Power, Sum — step through or auto-play.
Write grammar rules in BNF, see railroad diagrams auto-generated, test if strings are valid. 7 preset grammars.
Interactive stacks (LIFO), queues (FIFO), and linked lists with push/pop/enqueue/dequeue animations and operation logs.
Write and run real SQL in the browser. 3 databases (School, Shop, Music), 20 guided exercises, schema viewer, Ctrl+Enter to run.
Walk through UNF → 1NF → 2NF → 3NF with 3 real examples. See why one big table causes problems.
Train a classifier, see decision trees form, explore supervised vs unsupervised vs reinforcement learning.
Build a smart home with virtual sensors, watch data flow, and explore IoT security risks.
Compare Waterfall, Agile, Spiral, V-Model and RAD with animated stage diagrams and pros/cons.
IaaS vs PaaS vs SaaS explained with the pizza analogy. See who manages what at each level.
Good vs bad design examples, 8 usability principles, colour contrast accessibility checker.
15 real-world scenarios — is it legal? Ethical? Covers GDPR, Computer Misuse Act, Copyright, and AI ethics.