IB Diploma · session May 2027

Computer Science

Guide first taught 2025 and first assessed May 2027.

Mocks: in the future, hold tight!

Theme A

The theory The syllabus content of this unit, explained in order. Read → Worked examples Answers written the way a scheme rewards, with the commentary that explains the marks. Read → Practice test A timed test on this unit, with the marks shown against each part. Read → Mark scheme What earns each mark, point by point, and what is accepted instead. Read →

The course in one page

The course in one page. Standard and higher level, for the guide first taught 2025 and first assessed May 2027 — your session is the very first sitting of this course.

Why that matters more here than anywhere else

November 2026 is the last sitting of the legacy course. May 2027 is the first sitting of this one. There are no past papers. There are no examiner reports. Almost every free resource online still describes the old course, which had options, a Paper 3, and different themes entirely.

Practically, this means two things. Revise only from material dated 2025 or later. And expect the specimen paper and the pre-seen case study, released through the Programme Resource Centre, to carry more weight than usual — they are the only authentic indication of how this course will be examined.

What changed

The syllabus is rewritten around two themes instead of core plus options.
Options are gone. There is no Paper 3.
The case study has moved into Paper 1 and is sat by SL and HL alike.
The internal assessment is redesigned.
Machine learning is now core content, which it was not before.
The course is taught in either Java or Python — your school chooses, and the same language is used in both papers and the IA.

The two themes

Theme A — Concepts of computer science (Paper 1)

A1	Computer fundamentals — number systems, logic, CPU architecture, operating systems
A2	Networks — topologies, protocols, the OSI/TCP-IP layers, security
A3	Databases — relational design, normalisation, SQL, transactions
A4	Machine learning — supervised and unsupervised learning, training, evaluation, bias

Theme B — Computational thinking and problem solving (Paper 2)

B1	Computational thinking — decomposition, abstraction, pattern recognition, algorithm design
B2	Programming — data types, control structures, functions, file handling
B3	Object-oriented programming — classes, objects, inheritance, polymorphism, encapsulation
B4	Abstract data structures and algorithms — stacks, queues, lists, trees, graphs; searching and sorting

The papers

	Standard level	Higher level
Paper 1 (Theme A, with case study section)	75 min, 50 marks	120 min, 80 marks
Paper 2 (Theme B)	75 min, 50 marks	120 min, 80 marks

Paper 1 Section B is set on a pre-seen case study issued annually before the session. You are expected to have researched it thoroughly and to have learned terminology specific to it. This is the most predictable source of marks in the whole course — it is the one part of the exam you can prepare for precisely — and it is routinely wasted by candidates who read the case study once.

Paper 2 is where you write code. Answers are marked on logic, not on whether they would compile, but they must be recognisably in your chosen language and unambiguous.

How it is marked

Point-based schemes. Three things decide grades:

Terminology is the marks. "It sends the data" scores nothing where the scheme wants "the packet is routed". Computer science schemes are unusually literal about vocabulary.

Trace tables must show every step. When asked to trace an algorithm, draw the table with a column per variable and a row per iteration. Marks are for the intermediate states, not just the final output.

In code answers, show the structure. Correct indentation, meaningful identifiers and a clear control flow earn marks even where a detail is wrong. Pseudocode is accepted only where the question permits it.

Assessment objectives

		Roughly
AO1	Knowledge	define, state, outline
AO2	Application	apply concepts to a given scenario, including the case study
AO3	Analysis and evaluation	compare solutions, justify a design decision, construct code

Command terms, and what each one obliges you to write

Term	What must appear on the page
State / Identify	The answer alone.
Define	A precise meaning.
Outline	A brief account, main points only.
Describe	What it is or does, in detail. No why.
Explain	The reason or mechanism.
Distinguish	Differences set against each other.
Compare	Similarities and differences (compare and contrast requires both explicitly).
Construct	Write the code, algorithm or diagram.
Trace	A table showing variable values at each step.
Deduce	A conclusion from given information, with reasoning.
Evaluate	A judgement supported by both strengths and limitations.
Justify	Reasons for a specific choice, ideally acknowledging the alternative.

Educerie · written from the published IB Diploma Programme structure for Computer Science, first assessment 2027. Original text. Paper durations and mark totals checked against the May 2027 examination schedule. Last reviewed 5 September 2026.