Educate in CS
For students, fellow educators, or self-learners.
Explore how computers work, learn to program, and connect the ideas, with notes and practice currently aligned with IB Computer Science.
Code examples in Java and PythonThe big picture
Every computer does the same four things
It takes input, runs a process, produces output, and saves to storage. You type on a keyboard (input), the CPU runs instructions (process), the screen shows results (output), and files are saved to disk (storage). Every topic on this site zooms into one part of this cycle.
Topics
Pick where you'd like to start
Each topic has notes, worked examples, and interactive exercises; most also have a teacher guide, with more being added. Organised by the six layers of the IB Computer Science syllabus, plus cross-cutting topics.
Information Layer
Programming Layer
Programming Fundamentals
Variables, data types, operators, Strings, exception handling, debugging.
Programming Constructs
Sequence, selection, iteration, methods: the three building blocks of every program.
Data Structures
1D and 2D arrays, ArrayLists, stacks, queues: choosing the right collection.
Algorithms
Searching, sorting, and Big-O notation: picking the right tool for the job.
OOP
Modelling problems as interacting objects: classes, encapsulation, inheritance, polymorphism.
File Processing
Reading and writing text files in Java and Python: read, write, append, and close safely.
Abstract Data Types
Building structures from scratch: linked lists, stacks, queues, BSTs, hash tables.
JavaFX Cookbook
Plug-and-play JavaFX recipes for building a desktop app: tables, dialogs, file pickers, charts, and more.
Software Development
The craft around the code: requirements, design, testing, documentation, and usable interfaces.
Operating Systems Layer
Applications Layer
Databases
How databases store and query structured data: relations, ERDs, normalisation, SQL.
Machine Learning
How machines learn from data: types of learning, training, evaluation, and neural networks. Stretch pages go further: LLMs, image generation, and AI beyond machine learning.
Communication Layer
IB CS Assessments
Internal Assessment
The 30-mark IB CS project: criteria, planning, development, evaluation.
Case Study
The 2027 case study, Generative AI for image creation: techniques, models, ethics, and exam strategy for Paper 1 Section B.
CS Extended Essay
A 4,000-word independent research essay in computer science: choosing a topic, framing a question, evaluating sources.
Practise as you learn
Five ways to practise
Multiple choice
Choose an answer and read the explanation.
Trace tables
Follow the code line by line and record how the variables change.
Code completion
Fill the blanks in a method or loop until the code works.
Spot the bug
Find the error and choose the correction.
Predict output
Read the code, predict its output and check your answer.
Study tools
Tools for studying
- Key Conceptsclear explanations with precise terminology
- Worked Examplesstep-by-step solutions
- Practice ExercisesCore, Extension, and Challenge levels
- Glossary Tooltipshover over or tap a highlighted term for its definition
- Connectionsprerequisites and related topics to explore next
- GitHub Classroomprogramming assignments with automated tests
- My Progresskeep track of reviewed pages and quiz scores in this browser on My Progress
- Works Offlineinstall the site as an app; pages you have visited stay readable without a connection