MskProdComputing

Year 7 · Y7.4 Understanding Computers · Lesson 2

Stretch tasks Binary

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 binary card to its denary card.

  • 12 cards: each binary has a denary
  • 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: Binary

Binary: the questions

Quiz Challenge, round 1: Quiz Blitz

  1. Why do computers use binary?

    • Computers cannot count past 2
    • It always uses less electricity
    • Circuits are either on or off
    • Binary is easier for people to read

  2. What is binary 00000101 in denary?

    • 101
    • 3
    • 6
    • 5

  3. What is binary 01001010 in denary?

    • 37
    • 148
    • 74
    • 75

  4. What is 12 in 8-bit binary?

    • 00001110
    • 00011000
    • 00001100
    • 00001010

  5. In binary, each column is worth twice the column to its right.

    • True
    • False

  6. Put these binary place values in order, from left to right.

    Number these 1 to 6.

    • 32
    • 16
    • 8
    • 4
    • 128
    • 64

  7. Convert binary 00010001 to denary.

  8. What is 50 in 8-bit binary?

    • 00110001
    • 00101010
    • 01010000
    • 00110010

  9. Which TWO of these binary numbers are even?

    Tick 2.

    • 00000011
    • 00000110
    • 00001000
    • 00000111
    • 00001001

  10. The largest number 8 bits can hold is 255.

    • True
    • False

  11. What should you always do before converting a number?

    • Write the place values down
    • Count on your fingers
    • Guess, then check
    • Convert it to hex first

  12. How many different digits does binary use?

    • 2
    • 10
    • 8
    • 16

Quiz Challenge, round 2: Quick Fire

  1. Explain why computers use binary rather than the ten digits we use. [2 marks]

  2. Convert binary 01100001 to denary, showing your working. [2 marks]

  3. Convert 100 to 8-bit binary, showing your working. [2 marks]

  4. How can you tell whether a binary number is odd or even? [2 marks]

Quiz Challenge, round 3: Big Think

  1. Explain, step by step, how to convert 77 into 8-bit binary. [4 marks]

  2. Compare binary and denary, and explain why computers use binary. [6 marks]

This or That: tick the right answer

  1. What is binary 00000011 in denary?

    • 11
    • 3

  2. Which binary number is bigger?

    • 10000000
    • 01111111

  3. What is 6 in 4-bit binary?

    • 0101
    • 0110

  4. Is binary 00001001 odd or even?

    • Odd
    • Even

  5. What is the leftmost column worth in 8-bit binary?

    • 256
    • 128

  6. Why is binary used inside computers?

    • It is easier for people to read
    • Circuits are on or off

  7. What is 11111111 in denary?

    • 255
    • 256

  8. Putting a 0 on the right of a binary number does what to its value?

    • Adds one to it
    • Doubles it

Memory Match: match each binary to its denary

BinaryDenary
A 000000011 45
B 000001002 16
C 000010103 128
D 000100004 10
E 001011015 4
F 100000006 1
Answers

Round 1: Quiz Blitz

  1. Circuits are either on or off Two states, on and off, are easy to tell apart reliably.
  2. 5 The 4 and the 1 columns hold a 1: 4 + 1 = 5.
  3. 74 64 + 8 + 2 = 74.
  4. 00001100 12 = 8 + 4.
  5. True 1, 2, 4, 8, 16, 32, 64, 128.
  6. 128 → 64 → 32 → 16 → 8 → 4 Each column is worth twice the one to its right.
  7. 17 16 + 1 = 17.
  8. 00110010 50 = 32 + 16 + 2.
  9. 00000110; 00001000 A binary number is even when its last bit, in the 1s column, is 0.
  10. True 128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 = 255.
  11. Write the place values down Every mistake comes from trying to do it in your head.
  12. 2 Binary uses only 0 and 1.

Round 2: Quick Fire

    • Circuits are either on or off
    • Two states are easy to tell apart reliably
    Model answer

    A circuit is either on or off, so two states are easy to tell apart reliably. Ten different voltage levels would be far harder to build and easier to get wrong.

    • Working: the 64, 32 and 1 columns hold a 1
    • The answer is 97
    Model answer

    64 + 32 + 1 = 97.

    • Working: 100 = 64 + 32 + 4
    • The answer is 01100100
    Model answer

    100 = 64 + 32 + 4, so it is 01100100.

    • Look at the last bit, in the 1s column
    • A 1 there means odd, a 0 means even
    Model answer

    Look at the last bit, in the 1s column. If it is 1 the number is odd, and if it is 0 the number is even.

Round 3: Big Think

    • Write down the place values from 128 to 1
    • Work from the left, asking whether each place value fits
    • 64 fits, leaving 13
    • Then 8, 4 and 1 fit
    • The answer is 01001101
    • Check by adding the place values back up
    Model answer

    First write down the place values 128, 64, 32, 16, 8, 4, 2, 1. Work from the left, asking whether each one fits. 128 does not fit, so write 0. 64 fits, leaving 13, so write 1. 32 and 16 do not fit. Then 8 fits, leaving 5, then 4 fits, leaving 1, then 2 does not fit and 1 fits. The answer is 01001101. Check: 64 + 8 + 4 + 1 = 77.

    • Denary has ten digits, 0 to 9
    • Binary has two digits, 0 and 1
    • Each denary column is ten times the one to its right
    • Each binary column is twice the one to its right
    • A circuit is either on or off
    • Two states are easy to tell apart reliably
    • Ten voltage levels would be harder to build and cause more mistakes
    Model answer

    Denary has ten digits, 0 to 9, and each column is ten times the one to its right: 1, 10, 100. Binary has two digits, 0 and 1, and each column is twice the one to its right: 1, 2, 4, 8 up to 128. Computers use binary because a circuit is either on or off. Two states are easy to tell apart reliably, while ten different voltage levels would be harder to build and more likely to cause mistakes.

This or That

  1. 3 2 + 1 = 3. Binary 11 is not eleven.
  2. 10000000 10000000 is 128. 01111111 is 127.
  3. 0110 6 = 4 + 2. 0101 is 5.
  4. Odd The last bit is 1, so it is odd: 8 + 1 = 9.
  5. 128 The eight columns are 1, 2, 4, 8, 16, 32, 64 and 128.
  6. Circuits are on or off Two states are easy to tell apart reliably.
  7. 255 128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 = 255.
  8. Doubles it Every digit moves one column left, where columns are worth twice as much: 101 is 5, 1010 is 10.

Memory Match

  • A 6 00000001: 1
  • B 5 00000100: 4
  • C 4 00001010: 10
  • D 2 00010000: 16
  • E 1 00101101: 45
  • F 3 10000000: 128