QR code scanner

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Quick Questions

Shade in the A or B circle for each question.

1. How does a QR code scanner capture the QR code?

A It uses a microphone to listen to the pattern

B It uses a camera to capture an image of the square pattern

2. How is data stored in a QR code?

A Across a 2D grid of black and white squares (modules)

B Only in a single row of vertical lines

3. Which holds much more data?

A A QR code

B A standard barcode

4. What do the three large squares in the corners of a QR code do?

A They show the scanner the orientation of the code

B They store the price of the product

5. A QR code is upside down or turned sideways. What happens?

A It cannot be read until it is turned the right way up

B It can still be read, because it can be scanned from any angle

Match the Pairs

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

Left column		Right column
1QR code scanner		AA QR code is two-dimensional, using a square grid of black and white modules, not just parallel lines. This is why it stores more data than a barcode.
2Three corner squares		BUses a camera to capture a 2D square grid of black and white modules and decodes the pattern into data such as a web address or text.
3A QR code stores data across a grid in two dimensions, so it holds much more data than a barcode, which only uses lines.		Chttps://www.example.com
4A QR code scanner can decode a pattern into a web address, so scanning a poster takes you straight to a website.		DPosition markers in three corners of a QR code that show the scanner its orientation, so the code can be read from any angle.
5A QR code is a 1D pattern of lines, like a barcode		EThe three corner squares show the scanner the orientation, so a QR code can be read from any angle and does not need to be upright.
6A QR code must be held upright to be scanned		F2D grid of modules

Definitions

QR code scanner

Fill in the Blanks

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

A QR scanner uses a ______ to capture the QR code image

A QR code is a __ grid of black and white squares called modules

A QR code has _____ corner squares that show its orientation

A QR code can be read from any _____

The scanner will ______ the pattern into data such as a web address

Spot the Error

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

Question 1

A image ← camera.capture()

B pattern ← findLines(image)

C data ← decode(pattern)

D OUTPUT data

Question 2

A image ← camera.capture()

B grid ← findGrid(image)

C data ← decode(grid)

D OUTPUT image

Question 3

A corners ← countSquares(grid)

B IF corners = 4 THEN

C rotate(grid)

Question 4

A image ← camera.capture()

B orient ← findCorners(image)

C data ← decode(image, 0)

D OUTPUT data

Question 5

A data ← encode(grid)

B IF isLink(data) THEN

C openBrowser(data)

D ENDIF

Answer Key

QR code scanner

Section A: Quick Questions

B — It uses a camera to capture an image of the square pattern

A — Across a 2D grid of black and white squares (modules)

A — A QR code

A — They show the scanner the orientation of the code

B — It can still be read, because it can be scanned from any angle

Section B: Match the Pairs

QR code scanner → Uses a camera to capture a 2D square grid of black and white modules and decodes the pattern into data such as a web address or text.

Three corner squares → Position markers in three corners of a QR code that show the scanner its orientation, so the code can be read from any angle.

A QR code stores data across a grid in two dimensions, so it holds much more data than a barcode, which only uses lines. → 2D grid of modules

A QR code scanner can decode a pattern into a web address, so scanning a poster takes you straight to a website. → https://www.example.com

A QR code is a 1D pattern of lines, like a barcode → A QR code is two-dimensional, using a square grid of black and white modules, not just parallel lines. This is why it stores more data than a barcode.

A QR code must be held upright to be scanned → The three corner squares show the scanner the orientation, so a QR code can be read from any angle and does not need to be upright.

Section C: Definitions

QR code scanner — Uses a camera to capture a 2D square grid of black and white modules and decodes it into data like a web address or text. It holds more data than a barcode and reads from any angle.

Section D: Fill in the Blanks

A QR scanner uses a camera
to capture the QR code image

A QR code is a 2D grid of black and
white squares called modules

A QR code has three corner squares
that show its orientation

A QR code can be read from any angle

The scanner will decode the pattern
into data such as a web address

Section E: Spot the Error

B — A QR code stores data across a two-dimensional grid of modules, not in lines like a barcode. The line should be pattern ← findGrid(image).

D — The scanner must output the decoded data, such as a web address or text, not the raw camera image. It should be OUTPUT data.

B — A QR code has three corner squares that show its orientation, not four. The line should be IF corners = 3 THEN.

C — The three corner squares give the orientation, so the scanner can read the code from any angle. Decoding must use orient, not assume the angle is 0.

A — A QR code scanner decodes the grid into data such as a web address. It does not encode. The line should be data ← decode(grid).