Use case diagram: system boundary and actors

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Where should actors be drawn in a use case diagram?

A Outside the system boundary box

B Inside the system boundary box

2. Which symbol is used to represent an actor?

A A rectangle with rounded corners

B A stick figure

3. What does the system boundary box show?

A What is inside the system and what is outside it

B The order in which tasks are completed

4. A student logs into a school library system to borrow a book. How should the student be shown?

A As a use case inside the boundary

B As an actor outside the boundary, linked to a use case

5. Which is a primary actor for an online shop?

A The customer who places an order

B The payment gateway that processes the card

Match the Pairs

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

Left column		Right column
1System boundary (rectangle)		AActors must be drawn outside the system boundary. Only use cases go inside the box.
2Stick figure labelled 'Student'		BCustomer -----> (Place Order)
3A primary actor starts an interaction with the system to achieve their own goal, so they are drawn on the left of the boundary.		CThe boundary box is the wrong way around. It should surround the use cases, and the actors should be outside it.
4A secondary actor is an external system or person that supports the use case. They are usually drawn on the right of the boundary.		DAn actor: a user or role outside the system who interacts with it, drawn as a stick figure beside the boundary box.
5A Teacher stick figure drawn inside the system boundary box next to the use cases		EA box drawn around the use cases that marks what is inside the system. Everything outside the box is not part of the system.
6A system boundary box drawn around only the actors, with the use cases left outside it		F(Process Payment) -----> Payment Gateway

Definitions

Use case diagram

Fill in the Blanks

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

_____ Student actor Librarian

_________ "Library System" { usecase "Borrow book" as UC1 }

rectangle "Library System" { _______ "Borrow book" as UC1 }

actor Student usecase "Borrow book" as UC1 _______ --> UC1

actor Librarian usecase "Borrow book" as UC1 UC1 --> _________

Spot the Error

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

Question 1

A System: Library App

B Actor: Student (inside box)

C Use case: Borrow book (inside)

D Link: Student -- Borrow book

Question 2

A System: Canteen Orders

B Actor: Student (oval)

C Use case: Order lunch (oval)

Question 3

A System: Online Shop

B Primary: Customer (starts)

C Secondary: Bank (starts)

Question 4

A Boundary box: Librarian

B Actor: Librarian (stick man)

C Use case: Add book (inside)

Question 5

A System: Gym Booking

B Primary: Member (stick figure)

C Secondary: Payment system

D Use case: Book class (outside)

E Member -- Book class

Answer Key

Use case diagram: system boundary and actors

Section A: Quick Questions

A — Outside the system boundary box

B — A stick figure

A — What is inside the system and what is outside it

B — As an actor outside the boundary, linked to a use case

A — The customer who places an order

Section B: Match the Pairs

System boundary (rectangle) → A box drawn around the use cases that marks what is inside the system. Everything outside the box is not part of the system.

Stick figure labelled 'Student' → An actor: a user or role outside the system who interacts with it, drawn as a stick figure beside the boundary box.

A primary actor starts an interaction with the system to achieve their own goal, so they are drawn on the left of the boundary. → Customer -----> (Place Order)

A secondary actor is an external system or person that supports the use case. They are usually drawn on the right of the boundary. → (Process Payment) -----> Payment Gateway

A Teacher stick figure drawn inside the system boundary box next to the use cases → Actors must be drawn outside the system boundary. Only use cases go inside the box.

A system boundary box drawn around only the actors, with the use cases left outside it → The boundary box is the wrong way around. It should surround the use cases, and the actors should be outside it.

Section C: Definitions

Use case diagram — A diagram showing actors (stick figures) outside a system boundary box, linked by lines to the use cases inside the box that they can do with the system.

Section D: Fill in the Blanks

actor Student
actor Librarian

rectangle "Library System" {
  usecase "Borrow book" as UC1
}

rectangle "Library System" {
  usecase "Borrow book" as UC1
}

actor Student
usecase "Borrow book" as UC1
Student --> UC1

actor Librarian
usecase "Borrow book" as UC1
UC1 --> Librarian

Section E: Spot the Error

B — Actors are people or systems outside the system, so they are drawn outside the system boundary box. The line should say (outside box).

B — Actors are drawn as stick figures. Ovals are used for use cases. The line should say (stick figure).

C — A secondary actor supports the use case, for example by processing a payment. It does not start it. The primary actor starts it, so it should say (assists).

A — The system boundary box is labelled with the name of the system, such as Library System. Librarian is an actor, and actors sit outside the box.

D — Use cases are the functions of the system, so they are drawn inside the system boundary box. The line should say (inside).