Context diagram (Level 0): system and entities

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. How many processes does a Level 0 context diagram show for the system?

A Several processes showing each internal step

B One process representing the whole system

2. Where is the system process placed on a context diagram?

A In the centre, with entities around it

B At the edge, with entities inside it

3. Which of these is an external entity for a school canteen ordering system?

A Calculate order total

B Student placing an order

4. What does the system boundary separate?

A The system from the external entities outside it

B One programming language from another

5. Which item should NOT appear on a Level 0 context diagram?

A Data stores

B External entities

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1context diagram		AA person, organisation or other system outside the system boundary that sends data to or receives data from the system.
2external entity		BAn external entity must be drawn outside the system boundary, not inside the process. It is a person or system that interacts with the system from the outside.
3The whole system is drawn as one single process in the centre of the diagram, with a name that describes the system.		C( 0 ) Library Loan System
4The system boundary separates the system process from the external entities that interact with it.		DA Level 0 diagram that shows the whole system as one process in the centre, with external entities around it outside the system boundary.
5Context diagram with the processes Login, Search and Borrow, plus a data store Book Records, all drawn inside		EA context diagram shows the system as ONE process only. It must not show several inner processes or data stores. These belong in a Level 1 data flow diagram.
6[Librarian] drawn inside the system process Library Loan System		F[Student] -> (Library Loan System) <- [Librarian]

Definitions

context diagram

Fill in the Blanks

Complete each line of code by filling in the missing parts.

Level _ diagram: one process in the centre

_______________: sends or gets data

Number of system processes: _

The system boundary encloses the _______

Entities sit _______ the system boundary

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A Context diagram (Level 0)

B Processes: Orders, Payments

C Entity: Student

D Student -> System: order

Question 2

A Entity: Library System

B Entity: Member

C Entity: Librarian

D Member -> System: book request

Question 3

A System: Gym Bookings

B Entity: Member

C Store: Member Records

D Member -> System: booking

Question 4

A System: Online Shop

B Entity: Customer

C Customer -> System

D System -> Customer: receipt

Question 5

A System: School Attendance

B Entity: Record attendance

C Entity: Parent

D Teacher -> System: roll

E System -> Parent: absence note

Answer Key

Context diagram (Level 0): system and entities

Section A: Quick Questions

B — One process representing the whole system

A — In the centre, with entities around it

B — Student placing an order

A — The system from the external entities outside it

A — Data stores

Section B: Match the Pairs

context diagram → A Level 0 diagram that shows the whole system as one process in the centre, with external entities around it outside the system boundary.

external entity → A person, organisation or other system outside the system boundary that sends data to or receives data from the system.

The whole system is drawn as one single process in the centre of the diagram, with a name that describes the system. → ( 0 ) Library Loan System

The system boundary separates the system process from the external entities that interact with it. → [Student] -> (Library Loan System) <- [Librarian]

Context diagram with the processes Login, Search and Borrow, plus a data store Book Records, all drawn inside → A context diagram shows the system as ONE process only. It must not show several inner processes or data stores. These belong in a Level 1 data flow diagram.

[Librarian] drawn inside the system process Library Loan System → An external entity must be drawn outside the system boundary, not inside the process. It is a person or system that interacts with the system from the outside.

Section C: Definitions

context diagram — A Level 0 diagram that shows the whole system as one process in the centre, with external entities around it outside the system boundary.

Section D: Fill in the Blanks

Level 0 diagram: one process in the centre

External entity: sends or gets data

Number of system processes: 1

The system boundary encloses the process

Entities sit outside the system boundary

Section E: Spot the Error

B — A context diagram shows the whole system as ONE process in the centre. It must not be split into several processes. It should read System: Canteen Ordering.

A — The system being built is the single central process, not an external entity. Line 1 should be System: Library System.

C — A context diagram has no data stores. Stores appear in the Level 1 DFD. The trainer is an external entity, so this should be Entity: Trainer.

C — Every data flow must be labelled with the data that moves. The flow is missing its label and should be Customer -> System: order.

B — External entities are people, organisations or other systems, not actions. Recording attendance is what the system does. This line should be Entity: Teacher.