MskProdComputing

Year 7 · Y7.4 Understanding Computers · Lesson 3

Stretch tasks Units and how everything is stored

Task 1

Quiz Challenge

A quiz game against four computer players, then short and long written answers.

  1. Quiz Blitz12 questions against the clock
  2. Quick Fire4 short answers
  3. Big Think2 long answers

About 20 minutes

Task 2

This or That

Pixel the cat asks 8 questions. Each has two answers: pick the right one.

  • Two answers to every question
  • A fish treat for every right answer
  • Streaks win Pixel shades, then a party hat

About 4 minutes

Task 3

Memory Match

Flip the cards two at a time to match each term card to its meaning card.

  • 12 cards: each term has a meaning
  • One peek at every card
  • Combo points for pairs found in a row

6 pairs, about 4 minutes

The games need JavaScript. Every question is below, with the answers at the end.

Read the lesson: Units and how everything is stored

Units and how everything is stored: the questions

Quiz Challenge, round 1: Quiz Blitz

  1. How many bits are in a byte?

    • 8
    • 4
    • 10
    • 1000

  2. Put these units in order, from smallest to largest.

    Number these 1 to 6.

    • Kilobyte
    • Megabyte
    • Gigabyte
    • Terabyte
    • Bit
    • Byte

  3. How many megabytes are in 2 gigabytes?

    • 200
    • 20
    • 2,000,000
    • 2000

  4. A nibble is 4 bits.

    • True
    • False

  5. In ASCII, capital A is 65. What is capital C?

    • 66
    • 68
    • 3
    • 67

  6. What is a character set?

    • The agreed list of characters and their numbers
    • A set of fonts
    • A list of passwords
    • A keyboard layout

  7. How many colours can an image with 1 bit per pixel show?

    • 1
    • 8
    • 256
    • 2

  8. Which TWO make an image file bigger?

    Tick 2.

    • A shorter file name
    • More pixels
    • More bits per pixel
    • Fewer colours
    • Fewer pixels

  9. How many colours can 8 bits per pixel show?

    • 256
    • 8
    • 16
    • 16 million

  10. What is sampling?

    • Choosing the best part of a song
    • Measuring a sound wave many times a second
    • Copying a song
    • Making a sound louder

  11. How many measurements does CD quality take every second? Type the number.

  12. Better quality always means a bigger file.

    • True
    • False

Quiz Challenge, round 2: Quick Fire

  1. Explain how text is stored in a computer. [2 marks]

  2. Why does a photo with more pixels take up more storage? [2 marks]

  3. What is sampling, and why does a higher sample rate make a bigger file? [2 marks]

  4. How many bytes are in 3 kilobytes? Show your working. [2 marks]

Quiz Challenge, round 3: Big Think

  1. A photo saved with 24 bits per pixel looks better than the same photo with 8 bits per pixel, but takes more storage. Explain why. [4 marks]

  2. Text, images and sound are all stored as binary numbers. Explain how each one is turned into numbers, and why better quality means bigger files. [6 marks]

This or That: tick the right answer

  1. Which is bigger, a kilobyte or a megabyte?

    • A megabyte
    • A kilobyte

  2. How many bits are in 2 bytes?

    • 16
    • 10

  3. In ASCII, capital A is 65. What is capital E?

    • 70
    • 69

  4. How many colours can 2 bits per pixel show?

    • 4
    • 2

  5. Which recording is more accurate?

    • Fewer samples per second
    • More samples per second

  6. A file is 5 GB. How many MB is that?

    • 500 MB
    • 5000 MB

  7. Which change makes an image file smaller?

    • Fewer bits per pixel
    • More pixels

  8. What do text, images and sound have in common inside a computer?

    • They are all stored as pictures
    • They are all stored as binary numbers

Memory Match: match each term to its meaning

TermMeaning
A Bit1 4 bits
B Nibble2 Measuring a sound wave over and over
C Byte3 One dot of colour in an image
D Pixel4 8 bits
E Sampling5 The agreed list of characters and their numbers
F Character set6 A single 1 or 0
Answers

Round 1: Quiz Blitz

  1. 8 A byte is 8 bits. Four bits is a nibble.
  2. Bit → Byte → Kilobyte → Megabyte → Gigabyte → Terabyte Each unit is bigger than the one before. From the kilobyte up, each is 1000 times the last.
  3. 2000 1 GB is 1000 MB, so 2 GB is 2000 MB.
  4. True A nibble is half a byte.
  5. 67 The characters are in order: A is 65, B is 66, C is 67.
  6. The agreed list of characters and their numbers Every character is given a number, and the character set is the agreed list.
  7. 2 One bit is 0 or 1: black or white.
  8. More pixels; More bits per pixel More pixels and more bits per pixel both mean more numbers to store.
  9. 256 8 bits give 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 = 256 colours.
  10. Measuring a sound wave many times a second Each measurement of the wave's height is stored as a number.
  11. 44100 CD quality takes 44,100 samples every second.
  12. True Better quality means more numbers, and more numbers mean a bigger file.

Round 2: Quick Fire

    • Each character is given a number
    • The number is stored in binary
    • Using an agreed character set, such as ASCII
    Model answer

    Each character is given a number from a character set such as ASCII, and that number is stored in binary.

    • Each pixel's colour is stored as a number
    • More pixels means more numbers to store
    Model answer

    Each pixel's colour is stored as a number, so more pixels means more numbers to store, which means a bigger file.

    • Measuring the height of the sound wave many times a second
    • More samples means more numbers to store
    Model answer

    Sampling means measuring the height of the sound wave many times a second and storing each measurement as a number. More samples each second means more numbers to store, so the file is bigger.

    • 1 kilobyte is 1000 bytes
    • The answer is 3000 bytes
    Model answer

    1 kilobyte is 1000 bytes, so 3 kilobytes is 3 x 1000 = 3000 bytes.

Round 3: Big Think

    • The bits per pixel decide how many colours each pixel can be
    • 8 bits give 256 colours
    • 24 bits give over 16 million colours
    • More colours make the photo smoother and more realistic
    • Each pixel needs three times as many bits, so there is more to store
    Model answer

    The number of bits per pixel decides how many colours each pixel can be. 8 bits give 256 colours, but 24 bits give over 16 million, so the photo has smoother, more realistic colours. But each pixel now needs three times as many bits, so there are more numbers to store and the file is bigger.

    • Text: each character is a number from a character set
    • Images: a grid of pixels, each with its colour stored as a number
    • More bits per pixel give more colours
    • Sound: the wave is sampled
    • Each measurement is stored as a number
    • Better quality needs more numbers
    • Which takes up more storage
    Model answer

    Text is stored by giving each character a number from a character set such as ASCII. An image is a grid of pixels, and the colour of each pixel is stored as a number; more bits per pixel give more colours. Sound is stored by sampling: measuring the height of the wave thousands of times a second and storing each measurement. Better quality always needs more numbers, which takes up more storage.

This or That

  1. A megabyte A megabyte is 1000 kilobytes.
  2. 16 Each byte is 8 bits: 2 x 8 = 16.
  3. 69 A is 65, B 66, C 67, D 68 and E 69.
  4. 4 2 bits give 00, 01, 10 and 11: four colours.
  5. More samples per second More measurements follow the wave more closely, but the file is bigger.
  6. 5000 MB 1 GB is 1000 MB, so 5 GB is 5000 MB.
  7. Fewer bits per pixel Fewer bits per pixel means fewer numbers to store, but also fewer colours.
  8. They are all stored as binary numbers Everything is turned into numbers, and every number is stored in binary.

Memory Match

  • A 6 Bit: A single 1 or 0
  • B 1 Nibble: 4 bits
  • C 4 Byte: 8 bits
  • D 3 Pixel: One dot of colour in an image
  • E 2 Sampling: Measuring a sound wave over and over
  • F 5 Character set: The agreed list of characters and their numbers