Explaining data representation to a peer

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Which explanation of how the letter A is stored is the clearest?

A The computer just knows what A looks like and keeps a picture of it in memory.

B Text is stored using ASCII codes. A is 65 because of ASCII, and 65 in binary is 01000001.

2. A friend says: 'A pixel is stored as three numbers for red, green and blue.' What is still missing from a complete explanation?

A How those numbers become binary, e.g. 255 is 11111111 in 8 bits

B Nothing, because the numbers are all you need to say

3. Which sentence starter works best for explaining WHY a number is used?

A The letter A is stored as 65 because ASCII gives every character a number.

B The letter A is stored as 65 and also it is a letter.

4. Which is the right order for explaining sound to a peer?

A Binary, then samples, then sound

B Sound, then samples (volume numbers), then binary

5. Which example shows a pixel going to RGB to binary?

A Red pixel is (255, 0, 0), and 255 is 11111111 and 0 is 00000000.

B Red pixel is (255, 0, 0), and that is the same as the word red in ASCII.

Match the Pairs

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

Left column		Right column
1A -> 65 -> 01000001		Asound -> samples 0, 40, 80 -> 00000000 00101000 01010000
2(255, 0, 0) -> 11111111 00000000 00000000		BAn image example: a red pixel has RGB numbers 255, 0 and 0, and each number is stored as 8 bits of binary.
3Explain the sound type with a because sentence: a sound is a list of volume samples, and each sample number is stored in binary.		CThis skips the middle step. A pixel must first be described by RGB numbers, and those numbers are then converted to binary.
4Explain the text type with a because sentence: a letter is stored as a number because ASCII gives each character a code, and the code is stored in binary.		DThis gives no data type chain or numbers. It should say sound is measured as samples, which are numbers, and the numbers become binary.
5Pixel -> binary directly, no numbers		Eletter B -> 66 -> 01000010
6Sound is stored as binary because it is loud		FA text example: the letter A has ASCII code 65, and 65 is stored as the 8-bit binary number 01000001.

Definitions

type -> numbers -> binary

Fill in the Blanks

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

Data type: text A is 65 because of _____ 65 in binary is 01000001

Data type: image A red pixel is R=___, G=0, B=0 255 in binary is 11111111

Data type: sound Sound becomes numbers by taking _______

Text, images and sound become numbers. Data is binary _______ computers use bits.

Data type: text A is 65, and 65 in binary is ________

Spot the Error

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

Question 1

A Data type: text

B Numbers: ASCII codes

C A is 97 because of ASCII

D 65 in binary is 01000001

Question 2

A Data type: image

B Numbers: RGB values per pixel

C Red is 0,0,255 because RGB

D 255 in binary is 11111111

Question 3

A Data type: sound

B Numbers: samples of volume

C Each sample is one measurement

D A sample of 5 is 00000110

Question 4

A Data type: image

B Letter B is 66 because ASCII

C 66 in binary is 01000010

Question 5

A Data type: image

B Numbers: ASCII codes per pixel

C Black is 0,0,0 because of RGB

D 0 in binary is 00000000

Answer Key

Explaining data representation to a peer

Section A: Quick Questions

B — Text is stored using ASCII codes. A is 65 because of ASCII, and 65 in binary is 01000001.

A — How those numbers become binary, e.g. 255 is 11111111 in 8 bits

A — The letter A is stored as 65 because ASCII gives every character a number.

B — Sound, then samples (volume numbers), then binary

A — Red pixel is (255, 0, 0), and 255 is 11111111 and 0 is 00000000.

Section B: Match the Pairs

A -> 65 -> 01000001 → A text example: the letter A has ASCII code 65, and 65 is stored as the 8-bit binary number 01000001.

(255, 0, 0) -> 11111111 00000000 00000000 → An image example: a red pixel has RGB numbers 255, 0 and 0, and each number is stored as 8 bits of binary.

Explain the sound type with a because sentence: a sound is a list of volume samples, and each sample number is stored in binary. → sound -> samples 0, 40, 80 -> 00000000 00101000 01010000

Explain the text type with a because sentence: a letter is stored as a number because ASCII gives each character a code, and the code is stored in binary. → letter B -> 66 -> 01000010

Pixel -> binary directly, no numbers → This skips the middle step. A pixel must first be described by RGB numbers, and those numbers are then converted to binary.

Sound is stored as binary because it is loud → This gives no data type chain or numbers. It should say sound is measured as samples, which are numbers, and the numbers become binary.

Section C: Definitions

type -> numbers -> binary — Name the data type, say which numbers represent it, then show how they become binary. Give a short example for each, e.g. A is 65 because of ASCII, and 65 is 01000001.

Section D: Fill in the Blanks

Data type: text
A is 65 because of ASCII
65 in binary is 01000001

Data type: image
A red pixel is R=255, G=0, B=0
255 in binary is 11111111

Data type: sound
Sound becomes numbers by taking samples

Text, images and sound become numbers.
Data is binary because computers use bits.

Data type: text
A is 65, and 65 in binary is 01000001

Section E: Spot the Error

C — In ASCII, capital A is 65. The number 97 is the code for lowercase a. The line should be: A is 65 because of ASCII.

C — In RGB the order is red, green, blue. Pure red is 255,0,0. The values 0,0,255 would make blue.

D — 5 in 8-bit binary is 00000101 (4 + 1). The binary 00000110 is 6, so it does not match the example.

A — A letter is text, not an image. The first line should name the data type correctly: Data type: text.

B — Pixels are represented by RGB values, not ASCII codes. ASCII is used for text characters. The line should say: Numbers: RGB values 0 to 255.