Writing measurable non-functional requirements

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Which non-functional requirement is measurable?

A The app must load really fast.

B The app must load the home screen in under 2 seconds.

2. Which usability requirement is measurable?

A A new user can book a ticket in 3 taps or fewer, without help.

B The app must be easy and fun to use.

3. Which reliability requirement is measurable?

A The website must hardly ever crash.

B The website must be available 99.9% of the time each month.

4. Which security requirement is measurable?

A Passwords must be at least 12 characters and locked after 5 failed log-in attempts.

B The system must have strong security.

5. Which accessibility requirement is measurable?

A All images must have alt text and text must have a contrast ratio of at least 4.5:1.

B The site must be accessible to everyone.

Match the Pairs

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

Left column		Right column
1The app must load each screen in under 2 seconds on a standard school Wi-Fi connection.		AAll text must have a colour contrast ratio of at least 4.5:1 and every image must have alt text.
2The system must be available 99.5% of the time during school hours, Monday to Friday.		BA measurable reliability requirement: it names a quality (uptime) and a testable target (99.5%).
3A measurable usability requirement gives a number that can be tested with real users.		CAt least 9 out of 10 new users must be able to book a tutor in under 3 minutes without help.
4A measurable accessibility requirement names a recognised standard or checkable feature.		DWords like 'fast' and 'easy' are vague opinions. There is no testable target, so you cannot check if the requirement is met.
5The app must be fast and easy to use.		E'Very secure' has no testable target, so nobody can check whether it has been achieved.
6The system must keep user data very secure.		FA measurable performance requirement: it names a quality (speed) and a testable target (under 2 seconds).

Definitions

measurable non-functional requirement

Fill in the Blanks

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

Performance: a page loads _____ 2 seconds

___________: the app is up 99.9% of the time

Usability: users sign up in under 2 _______

Security: login locks after 3 ______ attempts

Accessibility: 100% of images have ___ text

Spot the Error

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

Question 1

A Performance requirement:

B Page loads quickly

C Search returns in under 1 sec

Question 2

A Usability requirement:

B Sign-up must be user friendly

C Menu is reached in 2 taps

Question 3

A Reliability requirement:

B The app should never fail

C Crashes under 1 per month

Question 4

A Passwords must be very secure

B Lock after 5 failed logins

C Log out after 10 min idle

Question 5

A Accessibility requirement:

B Text can be resized to 200%

C Text is easy to read for all

Answer Key

Writing measurable non-functional requirements

Section A: Quick Questions

B — The app must load the home screen in under 2 seconds.

A — A new user can book a ticket in 3 taps or fewer, without help.

B — The website must be available 99.9% of the time each month.

A — Passwords must be at least 12 characters and locked after 5 failed log-in attempts.

A — All images must have alt text and text must have a contrast ratio of at least 4.5:1.

Section B: Match the Pairs

The app must load each screen in under 2 seconds on a standard school Wi-Fi connection. → A measurable performance requirement: it names a quality (speed) and a testable target (under 2 seconds).

The system must be available 99.5% of the time during school hours, Monday to Friday. → A measurable reliability requirement: it names a quality (uptime) and a testable target (99.5%).

A measurable usability requirement gives a number that can be tested with real users. → At least 9 out of 10 new users must be able to book a tutor in under 3 minutes without help.

A measurable accessibility requirement names a recognised standard or checkable feature. → All text must have a colour contrast ratio of at least 4.5:1 and every image must have alt text.

The app must be fast and easy to use. → Words like 'fast' and 'easy' are vague opinions. There is no testable target, so you cannot check if the requirement is met.

The system must keep user data very secure. → 'Very secure' has no testable target, so nobody can check whether it has been achieved.

Section C: Definitions

measurable non-functional requirement — A quality of a solution, such as speed, security or usability, written with a testable target, like a page loads in under 2 seconds, so you can check whether it is met.

Section D: Fill in the Blanks

Performance: a page loads under 2 seconds

Reliability: the app is up 99.9% of the time

Usability: users sign up in under 2 minutes

Security: login locks after 3 failed attempts

Accessibility: 100% of images have alt text

Section E: Spot the Error

B — 'Quickly' is vague and cannot be tested. A measurable requirement needs a target, such as 'Page loads in under 2 secs'.

B — 'User friendly' has no testable target. It should be measurable, such as 'New user signs up in 3 min'.

B — 'Never fail' is not a testable target. Reliability needs a measurable figure, such as 'Uptime is at least 99.5%'.

A — 'Very secure' cannot be checked. A security requirement needs a target, such as 'Passwords need 8+ characters'.

C — 'Easy to read for all' is vague. An accessibility requirement needs a testable target, such as 'Text contrast ratio is 4.5:1'.