Software Engineering › Key terms › Diagrams and tools › Data flow diagram (DFD)
Data flow diagram (DFD)
Diagram Key terms bank Diagrams and tools
Also listed as: DFD
Definition
A diagram that shows how data moves through a system between processes, data stores and external entities.
Example: Voting system: voter, vote data, count.
Found in: syllabus, course specifications, school notes, past SDD papers.
Data flow diagram.
Where it is used in the test
Syllabus area: Diagrams and tools.
Question types it can appear in
- Drawing: Draw or complete a DFD
- Short answer: Define, outline or explain it and tie it to the scenario.
- Multiple choice: Pick the option that matches the definition or example.
Where it has appeared in the paper
The Software Engineering Project (Part D). Part letters follow each paper’s own layout.
Related past questions
- 2024 Software Design and Development HSC Q24 (10 marks): Social and ethical issues The Software Engineering Project (Part D) · 10 marks · old syllabus
- 2024 Software Design and Development HSC Q25 (4 marks): Documentation The Software Engineering Project (Part D) · 4 marks · old syllabus
These are the questions the flashcard set links to this term. Open each one and compare your answer with its marking criteria.
Study links
- Flashcard: Data flow diagram (DFD) in Diagrams and Modelling Tools (Years 11 and 12) · study that set
- Memorise: Drawing rules: DFD, structure chart, storyboard, decision tree, class diagram, ERD
- Key terms bank entry: DFD
- Master answer: sdd2024-q24 (10 marks, extended) (Master model answers: The Software Engineering Project (written answers))
- Notes: Modelling tools: DFD, structure charts, storyboards, flowcharts, class diagrams (The Software Engineering Project (Year 12))
- Notes: Drawing rules: DFD, structure chart, storyboard, decision tree, class diagram, ERD (Pseudocode, flowcharts and diagram rules)
- Notes: Interpret and apply fundamental software development steps to develop secure code,… (Secure Software Architecture (Year 12))
How to use it in an answer
A model sentence
Diagram: “A diagram that shows how data moves through a system between processes, data stores and external entities.” Then apply it: Voting system: voter, vote data, count.
In a short answer, give the definition in your own words first, then tie it to the situation in the question. Do not copy the example above unless it fits the scenario.
Command words used with it
- Explain: Relate cause and effect; make the relationship between things evident; provide why and/or how. (2024 Software Design and Development HSC Q25 (4 marks): Documentation)
Technique for the question types
- Drawing: Use the online drawing tool: label every symbol and arrow, use the correct symbols from the specification, and add every required item.
- Short answer: One clear point per mark, use the stimulus and course terms, and answer the command word.
- Multiple choice: Read all four options, rule out wrong ones, pick one; no penalty for guessing so never leave blank.
What the marking guidelines and feedback say
Old-syllabus question. Use for practice on the overlapping skill only. The new Software Engineering exam does not use the old SDD terms (e.g. CASE tools, system flowcharts, EBNF, assembly).
Old-syllabus question. Use for practice on the overlapping skill only. The new Software Engineering exam does not use the old SDD terms (e.g. CASE tools, system flowcharts, EBNF, assembly).
Common mistakes
- Drawing questions (2025 HSC exam Q22): refine attributes into separate inherited classes; use appropriate class diagram symbols.
- Use the term exactly as the syllabus words it, then link it to the scenario in the question; the 2025 feedback repeatedly rewards using the stimulus.
- Answer the command word: outline gives main points only, explain gives a reason or cause, discuss gives both sides.
Related terms
Same group in the syllabus: DFD process (circle) · DFD data store · DFD external entity · DFD data flow (labelled arrow) · Level 0 DFD (context diagram) · Level 1 DFD