Hamilton College · Year 12 · 2026

When you update your analytical tools in C3-1 (Step 1), you need to reproduce a Use Case Diagram, a Context Diagram, and a Data Flow Diagram. Setting up the notation from scratch each time costs 15–20 minutes and introduces layout errors. This page explains what is in the pre-labelled Excalidraw template and how to use it.

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The Excalidraw file (`C03-Analytical-Tools.excalidraw`) has three pre-built diagram skeletons on a single canvas, each with placeholder nodes labelled by notation role:

| Diagram | Pre-built elements |

|---|---|

| **Use Case Diagram (UCD)** | System boundary box; actor stick figures (primary user, secondary user); labelled oval placeholders for use cases; `«include»` and `«extend»` relationship stubs |

| **Context Diagram** | Central process circle (labelled with your system name placeholder); external entity rectangles on each side; labelled data-flow arrows in and out |

| **Data Flow Diagram (DFD)** | Level 1 layout with process circles, data store open rectangles, external entity rectangles, and directional arrow stubs; numbered process placeholders |

All three diagrams use the standard Yourdon–DeMarco notation that VCAA markers expect.

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1. **Download the file** — ask your teacher for `C03-Analytical-Tools.excalidraw`.

2. **Open in Excalidraw** — go to [excalidraw.com](https://excalidraw.com) and drag the file onto the canvas, or use the **Open** menu.

3. **Replace placeholders** — click each labelled placeholder and type your own system name, actor names, use cases, data stores, and process names.

4. **Add or remove elements** — copy a placeholder shape to add more use cases, or delete extras. Keep the notation style consistent (don't mix shapes between diagram types).

5. **Export** — when done, export as PNG or SVG to paste into your SRS document.

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Coming back to these diagrams from C02, check:

- **New actors**: has your scope change added a new type of user? Add them to the UCD.

- **New data flows**: does your updated scope require new data in or out? Update the Context Diagram arrows.

- **New processes**: does the DFD reflect how data now moves through the updated system?

The rubric at 7–8 band requires diagrams that accurately reflect your current SRS — not your C02 version. Change what has changed; don't just copy-paste from C02.

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| Symbol | Meaning |

|---|---|

| Stick figure | Actor (a person or external system that interacts with yours) |

| Oval | Use case (a goal the actor achieves using the system) |

| Rectangle | System boundary (what is inside vs outside the scope) |

| `«include»` arrow | Use case A always includes use case B |

| `«extend»` arrow | Use case B optionally extends use case A |

| Symbol | Meaning |

|---|---|

| Circle | The system (one only — this is a Level 0 DFD) |

| Rectangle | External entity (person, group, or system outside your scope) |

| Arrow with label | Data flow (label = what data moves, direction = which way) |

| Symbol | Meaning |

|---|---|

| Circle | Process (transforms data; numbered: 1.0, 2.0…) |

| Open rectangle | Data store (where data is held; labelled D1, D2…) |

| Rectangle | External entity (same as context diagram) |

| Arrow with label | Data flow |

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- [Functional vs Non-Functional Requirements](/sd/C03/Functional%20vs%20Non-Functional%20Requirements) — requirements that feed into your diagrams

- [Scope vs Constraints](/sd/C03/Scope%20vs%20Constraints) — what determines the system boundary in your UCD and Context Diagram

- C03 Resources: [external reading and videos](/sd/Resources/C03-Resources)

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