DP Computer Science · HL / SL · B1 Computational thinking

B1.1 Approaches to computational thinking

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  1. Question 1

    A local library wants to build a computer system that automatically reserves books for members and sends overdue reminders. Which of the following is the BEST problem statement to include in the project specification?
    No clue? Show me the answer
    Correct answerCorrect!Incorrect
    BLibrary staff spend approximately 3 hours per day manually processing book reservations and sending overdue notices by phone, resulting in delayed member notifications and frequent double-bookings.

    Step-by-step walkthrough

    Choose a solution method

    Method #1Direct approach

    Step 1: Identify what makes a strong problem statement

    A good problem statement must be specific, measurable, and consequential — it should explain exactly what the problem is, quantify the impact, and link it to a real negative outcome.

    Step 2: Analyse each option against these criteria

    Option A uses the vague phrase 'has problems' with no specifics. Option C says 'outdated and staff are unhappy' — still vague and unmeasurable. Option D gives a partial description but no quantified impact or cause.

    Step 3: Evaluate the strongest option

    Option B states the specific problem (manual processing), gives a measurable impact (3 hours per day), names the process causing harm (phone notifications), and identifies real consequences (double-bookings, delayed notifications).

    Step 4: Select the correct answer

    Option B satisfies all criteria for a strong problem statement: it is specific, measurable, and consequential. This makes it the clear best choice.

    Method #2Process of Elimination

    Step 1: Identify the question focus

    The question asks for the best problem statement, meaning the most specific, measurable, and consequence-linked description of the problem.

    Step 2: Eliminate 'The library system has problems...'

    'Has problems' is extremely vague — it tells a developer nothing about what specifically needs fixing or why it matters. This is eliminated immediately.

    Step 3: Eliminate 'the current one is outdated and staff are unhappy'

    'Outdated' and 'unhappy' are subjective and unmeasurable. There is no quantified impact or specific workflow identified, so this option fails.

    Step 4: Eliminate 'Members sometimes cannot reserve books...'

    While slightly more specific, 'sometimes' is not measurable, and no root cause or consequence is clearly linked. This is too weak to be a strong problem statement.

    Step 5: Select the remaining correct answer

    The option mentioning 3 hours per day, manual processing, and double-bookings is the only one that is specific, measurable, and consequential — it is the correct answer.

  2. Question 2

    A hospital uses a flowchart-based algorithm to process patient appointment bookings. Staff report that some patients are being assigned to the wrong department (for example, a cardiology patient is booked into neurology). Which computational thinking approach is MOST appropriate for identifying the source of this error?
    No clue? Show me the answer
    Correct answerCorrect!Incorrect
    CAlgorithmic design — trace through the flowchart step by step with sample inputs to identify where the decision logic produces an incorrect department assignment.

    Step-by-step walkthrough

    Choose a solution method

    Method #1Direct approach

    Step 1: Identify the nature of the problem

    The algorithm (flowchart) is producing incorrect outputs — patients are being routed to wrong departments. This is a logic error within the algorithm itself.

    Step 2: Determine which concept addresses algorithm logic errors

    Algorithmic design involves creating and analysing step-by-step logical instructions. Tracing an algorithm with test inputs is the standard technique for identifying where logic diverges from intended behaviour.

    Step 3: Confirm why other concepts do not apply

    Abstraction would not help trace a specific logic error. Deleting bookings (pattern recognition misapplied) destroys data rather than finding the fault. Separating departments (decomposition misapplied) does not fix the decision logic.

    Step 4: Select the correct answer

    Tracing the flowchart step-by-step with sample inputs is a direct application of algorithmic design and is the correct approach for diagnosing incorrect decision logic.

    Method #2Process of Elimination

    Step 1: Identify what the question is asking

    The question asks which computational thinking approach best identifies where a logic error occurs in a flowchart algorithm.

    Step 2: Eliminate the abstraction option

    Deleting and re-entering all patient data does not address the decision logic in the flowchart — it would simply recreate the same error. This is not what abstraction means in this context.

    Step 3: Eliminate the pattern recognition option

    Finding and deleting incorrect bookings treats the symptom, not the cause. This does not identify where the algorithm goes wrong, and deleting records would be harmful.

    Step 4: Eliminate the decomposition option

    Physically separating departments does not address the flowchart's decision logic error and misrepresents what decomposition means in computational thinking.

    Step 5: Select the algorithmic design option

    Tracing the flowchart step-by-step with sample inputs directly targets the logic error in the algorithm — this is the correct and precise application of algorithmic design.

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