The Complete IB DP Computer Science Preparation Guide (2027 Syllabus)
IB DP Computer Science was rebuilt for first assessment in 2027, and the fastest way to lose marks is to prepare against the old format. This guide maps the new two-theme syllabus, compares the SL and HL papers component by component, and lays out a study sequence that fits a two-year DP run. Everything here reflects the 2025 subject guide — the document your exams are written against.
The course at a glance
The new course is organised into two themes instead of the old four-course structure:
| Theme | Title | SL hours | HL hours |
|---|---|---|---|
| A | Concepts of Computer Science | 37 | 70 |
| B | Computational Thinking & Problem-Solving | 113 | 170 |
Theme A is the theory spine. Theme B is where the marks pile up — roughly three-quarters of your teaching time — because it is where programming, object-oriented design and algorithmic thinking live. SL students receive 150 teaching hours in total, HL students 240.
What Theme A covers
Four units, all taken by SL and HL:
- A1 Computer Fundamentals — von Neumann architecture, data representation, logic gates, operating systems, control systems, cloud computing
- A2 Networks — network types, devices and protocols, topologies, client-server vs peer-to-peer, segmentation and VLANs
- A3 Databases — relational databases, SQL, normalisation, data warehouses, NoSQL
- A4 Machine Learning — ML fundamentals, approaches, data preprocessing, and the ethical questions that follow
Theme A rewards students who can explain, not just recite: most extended-response questions ask you to apply a concept to a scenario rather than define it.
What Theme B covers
- B1 Computational Thinking — decomposition, abstraction, pattern recognition, algorithmic design, flowchart tracing, and Big-O analysis (yes, Big-O is now on the SL path)
- B2 Programming — program constructs, data structures including stacks and 2D arrays, string handling, file I/O
- B3 Object-Oriented Programming — SL needs a single class; HL adds multiple classes: inheritance, polymorphism, abstract classes, interfaces
- B4 Abstract Data Types — HL only: the classic structures (stacks, queues, linked lists, trees) with operations and use cases
If you are HL, B4 and the multi-class OOP extension are where the paper separates the 6s from the 7s. If you are SL, your battle is mostly precision in B1 and B2.
The papers, compared
| Component | SL | HL |
|---|---|---|
| Paper 1 | 35% · 1h 15m · 50 marks | 40% · 2h · 80 marks |
| Paper 2 | 35% · 1h 15m · 50 marks | 40% · 2h · 80 marks |
| Internal Assessment | 30% | 20% |
Paper 1 (Theme A) has two sections. Section A is extended response on the concepts; Section B is short response on a pre-seen case study — released roughly 12 months before a May exam (18 months before November), which means your class should be studying it months before the exam, not the week before.
Paper 2 (Theme B) is extended response on computational thinking and programming, and includes at least one question on algorithmic thinking without code — you reason about an algorithm in prose and structure rather than writing a program. Both papers split their marks 50/50 between knowledge-and-application (AO1+AO2) and the harder analysis objectives (AO3). Half the paper is asking you to think out loud in exam-acceptable form.
Java or Python?
Every code question is published in both Java and Python — you answer in whichever you were taught, and the IA is your free choice. Two practical notes from teaching both:
- School first. If your school teaches Java, prepare in Java; switching languages mid-DP costs more than it saves.
- Watch the built-ins rule. Python conveniences like
sort()are encouraged in the IA but can be prohibited in specific exam questions, where you must show the algorithm yourself. Practise writing the manual version of anything you rely on.
Either language can score a 7. The exam marks your thinking, not your syntax loyalty.
A study sequence that works
- Term-by-term, theme-first. Keep a single running document per unit. When you finish A2 Networks, your document should already answer “explain this to a friend” questions without the textbook.
- Case study from day one of year 2. Annotate it like a set of mark-scheme prompts, because that is what Section B of Paper 1 is.
- Code by hand, weekly. Paper 2 includes no-code algorithm questions, but writing code by hand is still the fastest way to internalise the logic those questions test.
- Command-term discipline. “State” wants one line; “explain” wants what and why; “evaluate” wants both sides then a judgement. Our command terms deep-dive breaks the full list into response depths.
- Start the IA early — properly early. It is worth 30% at SL and 20% at HL, and its criteria reward planning that happens before coding. Our IA guide walks each criterion and where the marks actually sit.
Where we come in
Distinction Academy teaches IB DP Computer Science for the 2027 syllabus at both SL and HL, online and in-person across Hong Kong. Classes pair a specialist CS tutor with our smart practice system — instant-feedback drills on definitions, command-term responses and algorithm tracing — plus our IB CS notes and sample packs. You can see the full teaching scope on the subjects page, or message us about a trial lesson.
Related reading: IGCSE Computer Science 0478 guide if you are bridging from IGCSE, or our HKDSE ICT complete guide for the DSE route.