Time 1.3 hrs

Difficulty Beginner
Prerequisites Computer Science A
Departments Science
Authors Sandra Kuipers
Groupings Individual
Minimum Year Group None


In this unit you will explore binary, bits and bytes.


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Learner Outcomes
Students will:
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Competency Focus
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Interdisciplinary Connections
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What was successful? What needs changing? Alternative Assessments and Lesson Ideas? What other Differentiation Ideas/Plans could be used?
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5 mins
All 0s and 1s
  • Computers are complex machines that work by storing the simplest of values:
    • 0 (also known as false or off)
    • 1 (also known as true or on)
  • This is called binary or base-2.
    • This unit won't teach you lots about binary, but there are other units that will.
    • For now you just need to know that computers use binary to store data.
  • In Computer Science we call a single 0 or 1 a bit (short form binary digit)
  • If you understand binary, you will get the following joke:

  • Don't worry if you don't get might soon!

5 mins
8 bit
  • In computers, groups of 8 bits are stored together in a Byte.
    • b stands for bit, B stands for Byte.
  • A byte will look something like this:
    • 10010111
  • A byte can be used to:
    • Store a number of 0 to 255.
    • Store a letter of the alphabet, and some other special symbols like !, ? or @.
5 mins
One and Zeroes
Getting Started

15 mins
Counting with Binary

20 mins
  • ASCII (pronounced as-key) is a system that computers use to store characters (letters, numbers, special symbols).
  • Instead of storing a letter directly, ASCII stores characters as numbers.
    • For example A is the number 65 and a is the number 97
  • You can use the chart below to see how different characters are represented as numbers in ASCII (click for a larger version):

  • I could use ASCII to write my name (Jody Hubert) as follows:

74 111 100 121 32  72 117 98 101 114 116 

  • Take some time now to write your name in ASCII.
  • However, as computers can only store binary, a computer would store my name as:

01001010 01101111 01100100 01111001 00100000 01001000 01110101 01100010 01100101 01110010 01110100  

Many, Many Bytes
  • Because computers store so much information, we often don't count in bytes, but use groups of bytes.
  • You may have heard of a gigabyte, or other groups such as kilobytes and megabytes.
  • The table below shows what these things are:

1 bit (b) = a single 0 or 1

1 byte (B) = 8 bits

1 kilobyte (KB) = 1024 bytes

1 megabyte (MB) = 1024 kilobytes

1 gigabyte (GB) = 1024 megabytes

  • This means that a gigabyte is a collection of 8,589,934,592 bits.
    • Or 1 x 8 x 1024 x 1024 x1024
    • That's a lot of data!
10 mins
Even more Numbers
  • If you want some even bigger numbers:

    1 terabyte (TB) = 1024 gigabyte

    1 petabyte (PB) = 1024 terabytes

    1 exabyte (EB) = 1024 petabytes

    1 zettabyte (ZB) = 1024 exabytes

    1 yottabyte (YB) = 1024 zettabytes

  • It is very hard to imagine how big these numbers are, but the image below might help you get a handle on the size of a petabyte:

20 mins
Finishing Up
  • To show what you have learned in this unit:
    • Create a Google Doc
    • Give the document a title
    • Add your name as author
    • Write your name in ASCII using regular numbers
    • Write your name in ASCII using binary numbers
    • Make a guess at how many bytes of information are contained in the whole English language version of Wikipedia.
    • How did you come up with that number?
  • When your Google Doc is ready, submit it as evidence of your learning in this unit. 
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