Data Flow Diagrams (DFD)

CAPE IT · UNIT 2 · MODULE 1 · OBJ. 6
Step 1 of 6

Watch the explainer video

5½ min · narrated walkthrough: symbols, a context diagram and a Level 1 DFD for a school library · captions available

Class activity: Human DFD — printable student sheets for a 40-minute group lesson.

EXPLORE IN 3D

A data flow diagram in 3D

Watch data move through a level 0 and a level 1 DFD.

REVISION · PAST-PAPER PRACTICE

Test yourself

Multiple-choice items in Paper 1 style and structured questions in Paper 2 style, adapted from CAPE Information Technology Unit 2 past papers. Your score and answers are saved on this device. When you have finished, submit them to your teacher at the end of this section.

MCQ best –Structured –

Paper 1 practice · 8 multiple-choice items

Choose one answer for each item, then check. Aim for 80% or better.

Adapted from CAPE U2 P1 2019 Item 10; 2020 Item 4
1. In a DFD for a library, four symbols are used: (1) a box labelled Student, (2) a rounded box labelled Loan book, (3) an arrow labelled Book details and (4) an open-ended box labelled Books. These represent, in order,
Answer: C. Student is outside the system (entity); Loan book changes data (process); the arrow carries data (flow); Books is where data is kept (store).
Adapted from CAPE U2 P1 2020 Item 8; 2022 Item 8
2. In Gane and Sarson notation, an open-ended rectangle with an ID such as D1 represents a
Answer: D. The open-ended rectangle with a D-number is a data store: data at rest.
Adapted from CAPE U2 P1 2020 Item 2
3. In a DFD of a bank’s account system, the calculations that keep customers’ balances correct are shown as a
Answer: A. Anything that transforms data, such as calculating a new balance, is a process.
Adapted from CAPE U2 P1 2019 Item 3
4. Which of the following data flows are ILLEGAL in a DFD?
I. From an external entity directly to another external entity
II. From an external entity directly to a data store
III. From a process to a data store
Answer: A. Every flow must start or end at a process. Process → store (III) is legal; I and II skip the process.
Adapted from CAPE U2 P1 2022 Item 10; 2024 Item 10
5. Part of a payroll DFD has a process 1.0 Find net pay with an arrow into it labelled Get next record. The diagram is incorrect because
Answer: B. Data flows carry data, so they are labelled with nouns (e.g. ‘employee record’). Verbs belong on processes.
Based on CAPE U2 P2 2026 Q2(b)
6. Which statement about a context-level DFD is TRUE?
Answer: C. The context diagram shows the system boundary: one process (0), the entities and the flows between them. Stores appear at Level 1.
EduTech practice item · Module 1 Obj. 6
7. A Level 1 DFD adds a flow refund going to the Customer that does not appear on the context diagram. The diagrams are
Answer: D. Internal flows may be added at Level 1, but flows to and from entities must match the context diagram exactly.
EduTech practice item · Module 1 Obj. 6
8. A process on a DFD has two input flows but no output flow. This error is called a
Answer: A. Inputs with no outputs make a black hole. Outputs with no inputs make a miracle.

Paper 2 practice · structured questions (18 marks)

Write a full answer to each part, then show the mark scheme and tick every point you earned. Marks for a part are capped at its maximum. Mark schemes are EduTech’s own; CXC does not publish them.

Based on CAPE U2 P2 May/June 2025, Question 1(c) and 2022, Question 2(a)(i)

Question 1 [8 marks]

At Parts Plus hardware store: a customer gives details of the items wanted; the order is recorded in the order system; a detailed bill is produced and a printed copy is given to the customer.

(a) Draw a Level 1 data flow diagram for this order process. [6]

MARK SCHEME (a) · max 6

(b) State TWO rules that must be followed when drawing a DFD. [2]

MARK SCHEME (b) · max 2
Based on CAPE U2 P2 May/June 2023, Question 2(b) and 2026, Question 2(b)

Question 2 [10 marks]

Pedal Island rents bicycles. A customer reserves a bike online (details, card number, bike type, date); the bike record is updated and the customer is emailed the reservation. At the shop the customer shows the reservation and ID and receives a lock and a rental agreement. On return, staff check the bike, print an invoice for the customer and update the bike record.

(a) Draw a context-level DFD for the bike rental system. [4]

MARK SCHEME (a) · max 4

(b) Draw a Level 1 DFD using only these THREE processes: 1 Reserve Bike, 2 Collect Bike, 3 Return Bike. [6]

MARK SCHEME (b) · max 6

Submit to your teacher

Send your multiple-choice choices and written answers to your teacher for marking. Your teacher will also see whether you opened the mark scheme or checked your answers before submitting. You can submit again if you improve your answers.

Items are adapted from CAPE® Information Technology Unit 2 Papers 01 and 02 (2019–2026) for practice. © Caribbean Examinations Council for the original papers.