To evaluate a screen, judge it against named criteria and give evidence from the screen. Three useful criteria are clarity, feedback and navigation.
This lesson is part of human computer interaction. The examples are original and fictional.
What do the three criteria ask?
| Criterion | Question to ask of the screen |
|---|---|
| Clarity | Can I tell what each item is and what it will do? |
| Feedback | Does the system tell me my action worked or failed? |
| Navigation | Can I see where I am and how to go back or forward? |
Ask each question in turn, and write down what you see before you write a judgement.
Worked example: a school kiosk
A library kiosk shows this screen. The title reads “Menu.” Three round icons appear with no labels. A student taps one, and the screen goes blank for two seconds, then shows the same three icons. There is no back button.
The three faults map to the three criteria.
| Problem | Where | Criterion | Fix |
|---|---|---|---|
| Icons have no text | The three round icons | Clarity | Add a short label under each, such as “Borrow” |
| Blank screen after a tap | After the tap | Feedback | Show “Loading” or a confirmation message |
| No way back | Whole screen | Navigation | Add a visible Back button and a page title |
Each row follows the same four-part pattern: problem, location, criterion, fix.
The mistake: a vague answer
A student writes: “The kiosk is hard to use and looks old.” That answer names no problem, no location and no criterion, so a marker has nothing to credit.
A stronger answer reads: “The three icons have no labels, so a new user cannot tell which one borrows a book. This reduces clarity. Adding a text label under each icon would fix it.”
The second answer uses the same observation but adds the location, the reason and the fix.
What makes feedback good?
Good feedback is quick, specific and visible. After a book is borrowed, “Atlas borrowed. Due on 14 March” is specific. A silent screen, or a message that says “Done” without saying what was done, is weak.
Error messages are feedback too. “Invalid input” gives no help. “Card number must be 8 digits” says what to fix.
Check yourself
A school canteen app lets a student press “Pay” and then shows an unchanged screen. The only way to see whether the payment worked is to open the history page, which sits under three menus. Name two problems with their criteria and a fix for each.
Answer
Feedback. Nothing on the payment screen says the payment worked or failed. Fix: show a confirmation such as “Payment of RM4.50 received” after pressing Pay.
Navigation. The history page is buried under three menus, so the user cannot easily verify the result. Fix: add a shortcut to “View receipt” on the confirmation message.
Any two problems earn credit when each is located, explained by a criterion and given a fix.
What to study next
Apply the same words when you design. Continue with designing an accessible input form for a fictional task, then practise on the cluster set.
Log the judgements you get wrong in the mistake log. If you want a teacher to go through your evaluations, see online one-to-one Computer Science tuition.