Show how the case study's systems work. Explain what they are meant to achieve, what each component does and how the components interact. This is an AO1 task: you need to demonstrate accurate knowledge and understanding, not simply name technologies.

The case study and Section B

Section B of Paper 1 uses the case study as a shared setting. The IB releases it before the examination, giving students time to investigate its systems and technologies. Section B tests understanding, application and reasoned judgement within that setting—not just recall of background information.

The examples in this sheet use an invented Larch Community Pantry, which reserves food parcels for collection. It is a teaching example, not an IB case study.

Explain the operation from beginning to end

When explaining a system, connect its purpose to its inputs, processing, stored data and outputs. Identify who uses it and any important dependencies too.

You also need to understand the system's limits. The reservation service depends on accurate stock records. If a donation has not been recorded, the service may report that no parcel is available even though one is physically present.

Terms: systems, knowledge and understanding.

Show how the problem has been organised so that a computer can help solve it. This AO1 objective focuses on the reasoning behind the system, rather than just its physical components or interface.

Connect computational thinking to actual behaviour

Tie each computational thinking idea to a decision or process in the case study. Relevant ideas may include breaking a problem into smaller tasks or retaining only necessary detail. Recognising repeated structures and designing precise procedures may also be relevant. The system described determines which ideas matter.

In the pantry, decomposition separates recording donations from checking availability and reserving parcels. Abstraction represents a parcel through the details needed for reservation, such as its identifier and availability, rather than every physical characteristic. To identify the steps that reservation requests share, use pattern recognition. Algorithmic thinking then arranges those steps in an unambiguous order.

Explain why the reasoning matters

Order matters. Checking availability before confirming a reservation helps avoid promising parcels that are unavailable. Once a reservation succeeds, updating the stored availability lets later requests use the changed stock position.

A complete account explains the procedure and why it follows that structure. Simply saying that the system “uses an algorithm” does not show what the algorithm achieves.

Terms: computational thinking, systems.

Use course knowledge to explain a particular feature, problem or decision in the case study. For this AO2 objective, recalling a general fact isn't enough. You need to use that fact to explain something in the given context.

Move from a concept to its consequence

A stock-entry form, for example, could reject a negative donation quantity. Validation checks whether entered data meets the system's rules, so this check stops a negative quantity from being accepted as a donation. It does not establish that the volunteer counted the donated parcels correctly.

Make the context change the explanation

The same system can draw on different concepts, each explaining a different aspect.

Treat these as illustrations, not a fixed list of technologies to use for every case study. Choose concepts that explain the systems actually described. Keep stated features distinct from changes you propose.

Terms: apply, concepts, context.

Explain a meaningful connection between the case-study scenario and another situation. For this AO2 objective, transfer your understanding while recognising where the comparison stops working.

Identify the shared problem

Different users may rely on systems that solve a similar computational problem. The pantry reserves a limited supply of parcels; a community workshop reserves a limited supply of tools. Each system must check availability, record an allocation and update availability.

Explain the limits of transfer

The design must account for the differences. Once collected, a food parcel is consumed. A borrowed tool, however, is expected to return, so the workshop needs to represent that return and restore the tool's availability. If it copied the pantry's process unchanged, this part of the workshop's problem would remain unsolved.

To explain a strong relationship, show what can transfer and what must change. Ground your reasons in the scenarios.

Terms: scenarios, concepts, context.

Discuss how the system affects people and organisations, including competing interests and ethical concerns. For this AO3 objective, build a balanced argument from the case-study circumstances. A list of generic advantages and disadvantages isn't enough.

Connect a feature to those affected

Begin with a system feature, then explain who it affects and what the consequence is. At the pantry, online reservations could save recipients unnecessary journeys because they can check availability before collection. An online-only service, however, could disadvantage recipients without reliable internet access.

Separate practical effects from ethical concerns

A practical effect describes what changes; an ethical concern asks whether that change treats people acceptably. Faster reservations offer an operational benefit. Excluding people who cannot access the service raises a fairness issue.

Which issues matter depends on the case study. For the pantry, examples include:

• Privacy: detailed recipient information may help organise support, but collecting unnecessary information exposes more personal information if records are misused.
• Fairness: giving every parcel to the earliest online requests is simple, but may favour recipients who can connect at the right time.
• Accountability: if a reservation is wrongly refused, recipients need a way to have the decision reviewed. They should not be left with an unexplained result.

Reach a qualified judgement

Volunteer-assisted reservations could reduce the access barrier, but they require staff time. Whether this approach is suitable depends on volunteers being able to support recipients without creating an unmanageable workload. Weigh that trade-off rather than assuming a safeguard has no cost.

Terms: impacts, ethical issues.

Develop possible responses, judge how suitable they are and defend your choice with evidence. This AO3 objective draws on the case study and your own research, alongside new stimulus material supplied in the examination.

Give each evidence source a role

Start with the case study: it sets out the original situation and constraints. Use research to understand the technologies and their limitations more deeply. New stimulus material may change a condition or add evidence. It may also raise a problem left unresolved in the original description.

For research to be useful, its relevance and credibility must be clear. A claim made for a different operating environment may not transfer directly to this one. Keep evidence separate from assumptions. A technology's advertised capability is not proof that it meets this system's needs.

Work through a changed situation

Take this entirely hypothetical teaching example. The original pantry system confirms reservations through a central service. Research into a proposed offline option establishes that its device uses a locally stored copy of stock records. Then new stimulus material reports a connection failure, with two volunteer devices handling requests.

The requirement is to keep helping recipients without promising the same parcel twice.

Working without a connection doesn't automatically make the offline option suitable. The detail about two devices exposes a conflict: their local records can disagree.

Justify the choice and state its limits

One defensible strategy is to record pending requests during the failure, then check them against central stock records before issuing confirmations. Request information is preserved, and recipients receive no unsupported promises. The cost is that they must wait for certainty.

This judgement is conditional: the strategy is suitable if delayed confirmation is acceptable. If immediate collection is essential, reconsider the alternatives against that requirement. Evaluation explains why a strategy fits the evidence and what it sacrifices. It also identifies which changed condition could alter the decision.

Terms: evaluate, formulate, justify, strategies, research, stimulus material.