← IGCSE Computer Science Paper 1

2D scanner

An input device that moves a light and sensor across a flat page or photo, reading the reflected light to capture a digital image made of pixels.

Part of: IGCSE Computer Science 0478 — 3.2 Input and Output Devices — Module 15

Understanding 2D scanner in IGCSE Computer Science Paper 1

What it does: This shows the order of events: the light source lights the page, light reflects off it and the sensor captures that reflected light. A 2D scanner saves the digital image as pixels, each one recording the colour or brightness of one tiny part of the page. A 2D scanner is an input device that digitises flat items such as photos and documents. A speaker is an output device for sound. OCR software looks at the shapes of the pixels and recognises letters, so the text can be edited in a word processor. A flatbed scanner has a glass surface for the page. A barcode scanner reads barcodes and is a different device.

Common mistakes: A 2D scanner's sensor reads reflected light from the page, not sound. Line 3 should be: sensor ← READ reflected light. To capture a digital image you press scan. Printing is done by a printer, which is an output device. Line 4 should be: PRESS scan.

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 2D scanner 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
Which statement describes how a 2D scanner captures a page?
A light and sensor move across the page and read the light reflected from itA laser burns the image into the paper and stores a copy as text
Matches
A 2D scanner outputs a printed copy of the page
↓
A scanner is an input device, not an output device. It captures a digital image of the page and sends it into the computer. A printer produces paper copies.
Applying
Meanings
Term
2D scanner
Meaning
An input device that moves a light and sensor across a flat page or photo, reading the reflected light to capture a digital image made of pixels.
Practice
PROCEDURE ScanPage()
Testing
Gaps
image ← (page)
Check Answer
Spots
2light ← MOVE ACROSS page
3sensor ← READ reflected sound

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

The 'Squirrel' badge — Module Hoarder, 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. Which statement describes how a 2D scanner captures a page?
A. A laser burns the image into the paper and stores a copy as text
B. A light and sensor move across the page and read the light reflected from it ✓
A 2D scanner shines light onto the document and its sensor reads how much light reflects back, building up a digital image.
2. A student wants to turn a printed photograph into a digital file. Which device is the best fit?
A. 2D scanner ✓
B. Speaker
A 2D scanner is an input device that digitises flat items such as photos and documents. A speaker is an output device for sound.
3. How is the image stored after a 2D scanner captures it?
A. As a grid of pixels ✓
B. As a single sound wave
The scanner records the colour or brightness of each tiny part of the page as a pixel, so the whole image is a grid of pixels.
4. What does optical character recognition (OCR) do?
A. Makes the scanned image print faster
B. Turns the scanned image of printed text into editable text ✓
OCR software looks at the shapes of the pixels and recognises letters, so the text can be edited in a word processor.
5. Which type of 2D scanner has a flat glass bed where you lay the document face down?
A. Flatbed scanner ✓
B. Barcode scanner
A flatbed scanner has a glass surface for the page. A barcode scanner reads barcodes and is a different device.

Match the Pairs

flatbed scanner → A 2D scanner where the document or photo lies face down on a glass plate while a light and sensor move beneath it
OCR → Optical character recognition: software that turns the scanned image of printed text into text that can be edited
A 2D scanner shines light onto the page, and the reflected light is read by a sensor → light -> page -> reflects -> sensor
The scanned image is stored as a grid of tiny coloured squares called pixels → image = grid of pixels
A 2D scanner outputs a printed copy of the page → A scanner is an input device, not an output device. It captures a digital image of the page and sends it into the computer. A printer produces paper copies.
Scanned text is automatically editable without OCR → A scan is only an image made of pixels. OCR software is needed to recognise the letters and turn them into editable text.

Key Term

2D scanner
An input device that moves a light and sensor across a flat page or photo, reading the reflected light to capture a digital image made of pixels.

Fill in the Blanks

1. image ← SCAN(page)
Hint: Type the operation name that captures the flat page as a digital image.
2. text ← OCR(image)
Hint: Type the abbreviation for the software that turns printed text in a scanned image into editable text.
3. reflected ← sensor.read(page)
Hint: Type the component that reads the light reflected off the page.
4. pixelCount ← width * height
Hint: Type the variable for the number of rows of pixels, which is multiplied by the width to give the total pixels in the saved image.
5. IF type = "text" THEN text ← OCR(image) ENDIF
Hint: Type the keyword that follows the condition and starts the code run when it is true.

Spot the Error

Question 1
A INPUT page ON glass
B light ← MOVE ACROSS page
C sensor ← READ reflected sound
D image ← SAVE AS pixels
Line C — A 2D scanner's sensor reads reflected light from the page, not sound. Line 3 should be: sensor ← READ reflected light.
Question 2
A OPEN lid
B PLACE photo FACE DOWN
C CLOSE lid
D PRESS print
Line D — To capture a digital image you press scan. Printing is done by a printer, which is an output device. Line 4 should be: PRESS scan.
Question 3
A image ← SCAN(letter)
B text ← OCR(image)
C text ← EDIT(text)
D SAVE image AS editable text
Line D — The scanned image is only pixels and is not editable. OCR creates the editable text, so the text variable should be saved. Line 4 should be: SAVE text AS document.
Question 4
A FOR each point on page
B colour ← READ(point)
C STORE colour AS letter
D NEXT point
Line C — A scanned image is saved as pixels, each holding a colour. It is not stored as letters. Line 3 should be: STORE colour AS pixel.
Question 5
A device ← FLATBED
B dimensions ← 3D
C OUTPUT dimensions
Line B — A 2D scanner captures a flat image of a flat page or photo. Capturing 3D shapes needs a 3D scanner. Line 2 should be: dimensions ← 2D.

Student with a class code? Join your class →