A colour key: whole numbers stand for colours

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Date:

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Quick Questions

Shade in the A or B circle for each question.

1. What does a colour key do?

A It locks a picture with a password

B It matches each number to a colour

2. The key says 1 = red, 2 = blue, 3 = yellow. What colour does a 2 in the grid show?

A Yellow

B Blue

3. Which key is a good way to set up a colour key for three colours?

A 1 = red, 2 = blue, 3 = yellow

B 1 = red, 1 = blue, 1 = yellow

4. A picture uses 0 for the background. What does that mean?

A Every 0 in the grid is the background colour

B Every 0 in the grid is a hole with nothing in it

5. Halfway through a picture, you can change the key so 1 means green instead of red.

A False

B True

Match the Pairs

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

Left column		Right column
11 = red, 2 = blue, 3 = yellow		A3 = yellow in every row of the grid
20 = white		BThe background colour is given the number 0 in the key
3A key lets a number stand for a colour, so a grid of numbers can show a picture		CA colour key that matches each whole number to one colour
4The same key must be used for the whole picture so each number always means the same colour		DThe number 1 is used for two different colours, so nobody can tell if a 1 is red or blue. Each number needs its own colour.
51 = red, 1 = blue, 2 = yellow		ERow 1: 1 2 2 1 (1 = red, 2 = blue)
6Row 1 uses 1 = red, Row 2 uses 1 = green		FThe key changes between rows. The key must stay the same for the whole picture so 1 always means the same colour.

Definitions

colour key

Fill in the Blanks

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

key: 1 = red, 2 = blue, 3 = yellow row: 1 _ 2 # red, yellow, blue

key: 0 = white, 1 = red, 2 = blue row: _ 1 1 0 # white, red, red, white

key: 1 = red, 2 = blue row1: 1 2 2 # red, blue, blue row2: 1 _ 1 # red, blue, red

key: 0 = white, 1 = ___, 2 = blue row: 1 2 0 # red, blue, white

key: 0 = white, 1 = red, 2 = blue row: 2 0 1 colours: blue, white, ___

Spot the Error

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

Question 1

A Key: 0=white 1=red 1=blue

B Row 1: 0 1 0

C Row 2: 1 2 1

D Row 3: 0 1 0

Question 2

A Key: 0=white 1=red

B Row 1: 0 1 0

C Row 2: 1 3 1

D Row 3: 0 1 0

Question 3

A Key: 0=white 1=green 2

B Row 1: 0 2 0

C Row 2: 2 1 2

D Row 3: 0 2 0

Question 4

A 0 = white

B 1 = red

C 2 = blue

D Row 1: red 2 1

E Row 2: 0 1 0

Question 5

A 0 = white (background)

B 0 = blue

C Row 1: 0 1 0

D Row 2: 1 1 1

Answer Key

A colour key: whole numbers stand for colours

Section A: Quick Questions

B — It matches each number to a colour

B — Blue

A — 1 = red, 2 = blue, 3 = yellow

A — Every 0 in the grid is the background colour

A — False

Section B: Match the Pairs

1 = red, 2 = blue, 3 = yellow → A colour key that matches each whole number to one colour

0 = white → The background colour is given the number 0 in the key

A key lets a number stand for a colour, so a grid of numbers can show a picture → Row 1: 1 2 2 1 (1 = red, 2 = blue)

The same key must be used for the whole picture so each number always means the same colour → 3 = yellow in every row of the grid

1 = red, 1 = blue, 2 = yellow → The number 1 is used for two different colours, so nobody can tell if a 1 is red or blue. Each number needs its own colour.

Row 1 uses 1 = red, Row 2 uses 1 = green → The key changes between rows. The key must stay the same for the whole picture so 1 always means the same colour.

Section C: Definitions

colour key — A list that matches each whole number to a colour, like 1 = red, 2 = blue and 3 = yellow, so a grid of numbers can show a picture.

Section D: Fill in the Blanks

key: 1 = red, 2 = blue, 3 = yellow
row: 1 3 2   # red, yellow, blue

key: 0 = white, 1 = red, 2 = blue
row: 0 1 1 0   # white, red, red, white

key: 1 = red, 2 = blue
row1: 1 2 2   # red, blue, blue
row2: 1 2 1   # red, blue, red

key: 0 = white, 1 = red, 2 = blue
row: 1 2 0   # red, blue, white

key: 0 = white, 1 = red, 2 = blue
row: 2 0 1
colours: blue, white, red

Section E: Spot the Error

A — Each colour needs its own number. In this key 1 stands for both red and blue, so blue should be 2=blue.

C — The key only has the numbers 0 and 1. The number 3 has no colour, so the row should be 1 1 1.

A — The key has to match every number to a colour. The number 2 has no colour here, so it should say 2=blue.

D — A picture grid is written with numbers, and the key turns them into colours. Row 1 should be 1 2 1, not the word red.

B — The number 0 is already the white background. Giving 0 a second colour confuses the key. Blue should be 1 = blue.