← IGCSE Computer Science Paper 1

Touch screen

A display that is also an input device: it detects where a finger or stylus touches it. Types are resistive, capacitive and infra-red. Used in phones, tablets, kiosks and ticket machines.

Part of: IGCSE Computer Science 0478 — 3.2 Input and Output Devices — Module 10

Understanding Touch screen in IGCSE Computer Science Paper 1

What it does: The screen outputs images to the user and also inputs the position of a touch to the computer, so it combines both roles. These devices let the user tap options on screen instead of using a separate keyboard or mouse. The screen shows output to the user and detects where it is touched, which is input. The three types are resistive, capacitive and infra-red. Ticket machines, kiosks, phones and tablets use touch screens so users can select options directly on the display. A stylus is used to touch the screen. An actuator is an output device that causes movement.

Common mistakes: The touch position is data coming in from the touch screen, so it must be read with INPUT, not OUTPUT. It should be INPUT touchX, touchY. The text to display must be inside quotation marks, otherwise it is treated as variable names. It should be OUTPUT "Finger works".

Class: _____________________  ·  Name: _____________________  ·  Date: _________

Free printable worksheet with full answer key — or add this module to a class and your students practise it interactively.

🖨 Print worksheet + answer key Add Touch screen to a class →

This module's key terms are also in a printable crossword (Modules 252–261) and word search (Modules 240–261).

Take this worksheet further — free with Cloodit

Each concept is reinforced from every angle — learned, then applied, then tested.

Learning
Duo
A touch screen is both an input device and an output device.
True: it displays images and also detects touchFalse: it is only an output device
Matches
A touch screen is only an output device
↓
A touch screen is an output device and an input device, because it also detects where a finger or stylus touches it.
Applying
Meanings
Term
touch screen
Meaning
A display that is also an input device: it detects where a finger or stylus touches it. Types are resistive, capacitive and infra-red. Used in phones, tablets, kiosks and ticket machines.
Practice
OUTPUT "Touch BUY TICKET"
Testing
Gaps
position FROM touchscreen
Check Answer
Spots
1OUTPUT touchX, touchY
2IF touchX > 200 THEN

Cloodit turns curriculum-aligned coding content into journeys students work through one biome at a time.

The 'Scorpion' badge — Venom Debugger, one of Cloodit's 106 collectible badges
Students earn collectable badges

Over 100 of them, across seven natural biomes.

Study Buddy
Students build a real study resource

Turns their work into revision material ready for Flash Cards and Exam study.

Diamond Dash — one of Cloodit's live, competitive Sprint games
Students lock in with Sprints

Live, competitive practice for the start of the lesson or a teacher-led lesson finisher.

A Cloodit certificate of achievement, ready to personalise and print
Custom printable certificates

Honour your top performers, or encourage a student who's trying hard — ready to print in seconds.

Add to class →

Quick Questions

1. A touch screen is both an input device and an output device.
A. True: it displays images and also detects touch ✓
B. False: it is only an output device
The screen shows output to the user and detects where it is touched, which is input.
2. Which pair lists the three types of touch screen in the syllabus?
A. Resistive, capacitive, infra-red ✓
B. Resistive, optical, magnetic
The three types are resistive, capacitive and infra-red.
3. What does a touch screen detect?
A. The sound of a user's voice
B. Where a finger or stylus touches the screen ✓
A touch screen finds the position of a touch. Detecting voice is the job of a microphone.
4. Which device is a typical use of a touch screen?
A. A barcode on a food packet
B. A ticket machine at a station ✓
Ticket machines, kiosks, phones and tablets use touch screens so users can select options directly on the display.
5. A touch screen means a phone does not need a separate keyboard to enter data.
A. True: an on-screen keyboard can be touched to type ✓
B. False: a phone always needs a physical keyboard
The display can show a keyboard and detect which key is touched, so input and output happen on the same screen.

Match the Pairs

touch screen → A display that is also an input device because it detects where a finger or stylus touches it
resistive, capacitive, infra-red → The three types of touch screen technology that detect where the screen is touched
A touch screen is both an input device and an output device in one → input: touch position, output: picture on display
Touch screens are used where users need to select options directly on the display, such as phones, tablets, kiosks and ticket machines → uses = [phone, tablet, kiosk, ticket machine]
A touch screen is only an output device → A touch screen is an output device and an input device, because it also detects where a finger or stylus touches it.
Touch screen types: resistive, capacitive, laser → The third type is infra-red, not laser. The three types are resistive, capacitive and infra-red.

Key Term

touch screen
A display that is also an input device: it detects where a finger or stylus touches it. Types are resistive, capacitive and infra-red. Used in phones, tablets, kiosks and ticket machines.

Fill in the Blanks

1. INPUT position FROM touchscreen OUTPUT menu TO touchscreen
Hint: Type the pseudocode keyword used to read data in from a device, because a touch screen is an input device.
2. IF touched = TRUE THEN OUTPUT menu ENDIF
Hint: Type the keyword that follows the condition in an IF statement.
3. screenType ← "capacitive"
Hint: Type the touch screen type that senses the electrical charge of a finger, as used in phones and tablets.
4. kiosk.input ← touchscreen kiosk.output ← touchscreen
Hint: Type the one device that also shows the display, so it is input and output in one.
5. IF touchCount > 0 THEN OUTPUT ticketMenu ENDIF
Hint: Type the comparison operator that means greater than, to check if the ticket machine screen was touched.

Spot the Error

Question 1
A OUTPUT touchX, touchY
B IF touchX > 200 THEN
C OUTPUT "Menu opened"
D ENDIF
Line A — The touch position is data coming in from the touch screen, so it must be read with INPUT, not OUTPUT. It should be INPUT touchX, touchY.
Question 2
A screen ← "capacitive"
B IF screen = "capacitive" THEN
C OUTPUT Finger works
D ENDIF
Line C — The text to display must be inside quotation marks, otherwise it is treated as variable names. It should be OUTPUT "Finger works".
Question 3
A count ← 0
B WHILE count < 3
C OUTPUT "Tap the screen"
D count ← count - 1
E ENDWHILE
Line D — Subtracting 1 means count never reaches 3, so the loop would never end. It should be count ← count + 1.
Question 4
A INPUT tapped
B IF tapped ← "Yes" THEN
C OUTPUT "Thank you"
D ENDIF
Line B — A condition compares values using =, but ← is the assignment arrow. It should be IF tapped = "Yes" THEN.
Question 5
A device ← "touch screen"
B isInput ← FALSE
C isOutput ← TRUE
D OUTPUT isInput AND isOutput
Line B — A touch screen detects touches, so it is an input device as well as an output display. It should be isInput ← TRUE.

Student with a class code? Join your class →