IB DP Computer Science B.1: Computational Thinking – Revision Notes

B.1 Computational thinking is the process that underpins the whole IB DP Computer Science course (first assessment 2027): specify the problem and its success criteria, decompose it, abstract and generalize it, then test and evaluate the solution. These notes summarise what the IB’s public subject brief says; the detailed learning outcomes are in the full DP guide, so check your school’s copy for exact content.

Full explanation: B.1 Computational thinking study guide.

Key facts from the subject brief

Item	What the brief says
Where it sits	Theme B, “Computational thinking and problem-solving”
Teaching hours	5 SL / 5 HL
Assessed in	Paper 2 (Theme B questions for SL and HL); applied in the computational solution (IA)
Paper 2	SL 1 h 15 min (35%); HL 2 h (40%); some questions need programming, in Java or Python
Internal assessment	Computational solution to a real-world problem of the student’s choosing; 35 hours; 30% SL, 20% HL

The four abilities (brief’s wording)

Ability	In the brief	What to be able to do
Specify	“specify problems in terms of their computational context and determine success criteria”	State the problem in computing terms and write testable success criteria
Decompose	“decompose complex real-world problems into more manageable problems”	Split a problem into smaller problems that can be solved one at a time
Abstract and generalize	“abstract problems and generalize them to enable algorithmic thinking and to develop solutions”	Keep what matters and express it generally so an algorithm can be designed
Test and evaluate	“test and evaluate solutions for improvements”	Check the solution against the success criteria and identify improvements

Linked assessment objectives

• AO3 includes constructing, analysing and evaluating “problem specifications, system requirements, success criteria, testing strategies, and programs”.
• AO4: “demonstrate the application of computational thinking skills to solve real-world problems using computer science solutions”.

Worked example: applying the cycle

Problem: a school club wants to know which members have not paid their subscription.

1. Specify: input is the member list with payment status; output is a list of unpaid members. Success criterion: every member with no payment recorded appears in the list, and no paid member does.
2. Decompose: read the member data; check each member’s payment status; collect the unpaid members; display the result.
3. Abstract and generalize: only the name and payment status matter, not addresses or ages; the “check each item against a condition” step is general and could be reused for any filter.
4. Test and evaluate: run with a list where some have paid and some have not, plus an empty list; compare the output with the success criterion; note an improvement such as sorting the output.

Common mistakes and exam traps

• Writing vague success criteria (“the program works well”) that cannot be tested.
• Treating decomposition and abstraction as the same thing: decomposition splits a problem up; abstraction removes detail that does not matter.
• Testing a solution without referring back to the success criteria set when the problem was specified.
• Learning B.1 as definitions only. The brief describes it as a process applied throughout the course.

Frequently asked questions

How many hours is B.1? 5 hours at SL and 5 hours at HL, according to the subject brief.

Is computational thinking only in B.1? No. The brief says the course is underpinned by the computational thinking process, and the internal assessment uses it.

Where do I find the exact B.1 learning outcomes? In the full DP Computer Science guide, available to IB schools through the Programme Resource Centre.

Self-test

1. List the four abilities computational thinking involves, according to the brief.
2. What must be determined when a problem is specified?
3. Which paper assesses Theme B?
4. How many teaching hours does B.1 have at HL?
5. Which assessment objective is about applying computational thinking to real-world problems?

Answers: 1. Specify (with success criteria), decompose, abstract and generalize, test and evaluate. 2. The success criteria. 3. Paper 2. 4. 5 hours. 5. AO4.

Related pages

• B.1 Computational thinking practice questions
• B.2 Programming revision notes

Source

International Baccalaureate Organization, Diploma Programme Subject Brief, Sciences: Computer science, first assessment 2027 (© 2024).