IB CS Hub

Already a student? Sign in

Free guide · IB Diploma · Computer Science · First examinations 2027

IB Computer Science 2027 Syllabus Guide

A plain-English map of what's actually in the course: the two themes, what HL adds on top of SL, how the two exam papers are structured, and how the Internal Assessment works. Also see the free glossary, a sample revision booklet, and a sample IA guide.

Two themes, nine units

The syllabus splits into Theme B (Programming), examined on Paper 2 in Python, and Theme A (Systems) plus a yearly Case Study, examined on Paper 1. B4 and A4 are HL-only; every other unit is shared between SL and HL, with extra HL-only lessons layered on top.

B1 · Computational Thinking

Specifying problems, abstraction, decomposition, and tracing flowcharts.

B2 · Programming

The Python toolkit: data types, control structures, functions, exceptions, stacks/queues, Big-O, search/sort, file processing.

B3 · Object-Oriented Programming

Classes, objects, encapsulation; HL adds inheritance, polymorphism, abstraction, composition and design patterns.

B4 · Abstract Data Types (HL only)

Linked lists, binary search trees, sets and hashmaps.

A1 · Computer Fundamentals

CPU components, memory, fetch-decode-execute, binary/logic gates; HL adds operating systems, scheduling, control systems, compilers.

A2 · Networks

Network types, devices, protocols, IP addressing and routing, firewalls, encryption.

A3 · Databases

Schemas, ERDs, normalization to 3NF, SQL; HL adds views, transactions, database types and data warehousing.

A4 · Machine Learning (HL only)

Preprocessing, regression, classification, clustering, reinforcement learning, neural networks, ethics.

Case Study · Generative AI

A new applied case study each exam cycle — diffusion models, GANs, hybrid approaches, and evaluating them.

How the exams are structured

Paper 1

Covers Theme A (A1 Computer Fundamentals, A2 Networks, A3 Databases, A4 Machine Learning at HL) plus the year's Case Study.

Paper 2

Covers Theme B (B1 Computational Thinking, B2 Programming, B3 OOP, B4 Abstract Data Types at HL) — all in Python.

Internal Assessment (IA)

A self-built, coded software product with supporting documentation, worth 30 marks across five tasks (A–E) — each builds on the last, and later tasks are graded against how well they stay consistent with Task A's success criteria.

Task A · 4 marks

Problem Specification

Task B · 4 marks

Planning

Task C · 6 marks

System Overview

Task D · 12 marks

Development

Task E · 4 marks

Evaluation

Want lesson-by-lesson decks for every unit above?

Full SL & HL lesson decks, revision handouts, exam-style practice with worked answer keys, a progress tracker, and AI-powered exam prep — one payment, one year of access.

See what's included →