~ Welcome to Secondary Level Computing


The wonderful world of Computer Science

In this topic (data representation) you're going to be amazed! There's so much to learn and much of it is going to sound like magic. Download the student powerpoint (end of task assessment) and go through it ahead of starting your learning. That way, you'll know what to look out for and what you'll need to know!

Let's start right at the beginning and ask the big questions. Have you ever wondered how our brain (essentially a lump of flesh) REMEMBERS? What is your computer anyway?

The brain is still a bit of a mystery, but computers are quite different. They are entirely man made. That means we understand them - well we created them didn't we?

So, how does a Computer remember? What is a computer anyway?

Did you know that the only "language" a computer understands is Binary? Binary is a language that is made up of just two digits: 1 and 0. 

What??!?!

How could that possibly be?

This whole topic is dedicated to DATA REPRESENTATION. To put it simply, we are looking at how computers represent data. How does a computer display everything from numbers, text, images, sound and video? 

Storing Numbers: Binary

Starter

Let's start by asking ourselves the question: "What is a Computer". 

Discussion Questions

Discuss in pairs / groups or as part of a class discussion

1. What did you think a computer was? What other questions do you have about computers and how they work?

2. Do you think a computer is more "powerful" than the brain? Why or why not? *it would of course depend on how you define the term "powerful" in this context.

3. Explain in your own words why you think early computers were so huge? How is it that computers now are far more compact and portable?

 

Main Lesson tasks:

1. Recap on Binary (refer to lesson 1 in the Scratch unit

Go through Lesson 1 again: (Slide 10 onwards) and reiew your knowledge and understanding of Binary!

 

2. Play the binary game and see how high you can score!

https://studio.code.org/projects/applab/iukLbcDnzqgoxuu810unLw

 

3. Read through the additional theory below and create a presentation (either in prezi, powerpoint or publisher (a leaflet) that explains the following

1. What is Computer Memory?

2. Explain in your own words how Computers store numbers?

3. Explain the term bits and bytes and use a table to show the values associated with KB, MB, GB etc.

4. Ahead of our learning in the next lessons, do some research on how Computers store text, sound, and video data. Explain this, as best you can, in your own words. 

5. Extension: What is the largest number a Computer can hold? Explain your research and reasoning. 

 

Theory and Links

Have you ever wondered how your brain (essentially a lump of flesh) REMEMBERS? Well, that's an entirely different topic which we won't get in to now, but the question is similar and as interesting when you ask yourself: How does a computer (which is just a bunch of circuits (that is on and off switches) REMEMBER? How does it have, what we call, a memory? Read on...and skip to following sections for the relevant topical powerpoints

File:Brain hirez.jpg

The language that a computer understands is very simple, so simple that it only has 2 different numbers: 1 and 0. This is called Binary. Everything you see on a computer, images, sounds, games, text, videos, spreadsheets, websites etc. Whatever it is, it will be stored as a string of ones and zeroes.

monochrome image of a smiley face

All stored as binary

 

Ccard icon.pngNuvola camera.svgNuvola apps looknfeel.pngNuvola apps kmplot.svg

 

Bit - a standard unit to measure computer memory, consisting of a value that is either 1 or 0

Byte - a standard unit to measure computer memory, usually consisting of 8 bits. e.g. 10101011

Exercise: Bit patterns in a Computer

How do computers store data?

Answer :

as binary values, using a pattern of 1s and 0s

What sort of data can be stored in binary?

Answer :

  • Video
  • Sound
  • Picture
  • Text
  • Code
  • Spreadsheet
  • Game
  • etc

What does the following binary string represent: 10011100

Answer :

This could be anything:

  • sound data
  • picture data
  • text ASCII for œ
  • unsigned integer = 156
  • video data
  • etc

How many bits in a byte?

Answer :

8, but it is originally the amount of bits used to represent a character

How many bits in 7 bytes?

Answer :

7 * 8 = 56

 

Independent Learining

This second video is rather long and very mathematical. You don't have to watch all of it, but it introduces the idea of Number Systems, which is crucial to what we are about to learn


Text is available under the Creative Commons Attribution-ShareAlike License https://en.wikibooks.org/wiki

Storing Text: Character Encoding

Starter:

How Computers store characters and text

Discussion Questions

Discuss in pairs / groups or as part of a class discussion

1. Do you think this is the most effective way to represent characters? Why or why not? 

2. Do a little research and discuss why you think all of these early developments and standardisation took place in America! Why not the UK, China or India?

Main Lesson Tasks

1. Go through the following powerpoint on ASCII

 

 

 

 

 

 

 

 

 

 

 

2. Research and Present

ASCII code can only store 128 characters, which is enough for most words in English but not enough for other languages. Create a presentation in which you explain in your own words and research the codes: UNICODE and EBDIC 

3. Theory and Links

The following chunk of information was taken from BBC Bitesize: http://www.bbc.co.uk/education/guides/zpfdwmn/revision

When any key on a keyboard is pressed, it needs to be converted into a binary number so that it can be processed by the computer and the typed character can appear on the screen.

The letter "A" on a keyboard converts to 01000001 in binary

A code where each number represents a character can be used to convert text into binary. One code we can use for this is called ASCII. The ASCII code takes each character on the keyboard and assigns it a binary number. For example:

  • the letter ‘a’ has the binary number 0110 0001 (this is the denary number 97)
  • the letter ‘b’ has the binary number 0110 0010 (this is the denary number 98)
  • the letter ‘c’ has the binary number 0110 0011 (this is the denary number 99)

Text characters start at denary number 0 in the ASCII code, but this covers special characters including punctuation, the return key and control characters as well as the number keys, capital letters and lower case letters.

ASCII code can only store 128 characters, which is enough for most words in English but not enough for other languages. If you want to use accents in European languages or larger alphabets such as Cyrillic (the Russian alphabet) and Chinese Mandarin then more characters are needed. Therefore another code, called Unicode, was created. This meant that computers could be used by people using different languages.

Independent Learning

Here's a great video on Computer Memory:

If you're interested you may also want to check out the following links that will give you further information on this excicting topic:

https://en.wikipedia.org/wiki/Character_encoding

https://en.wikipedia.org/wiki/ASCII

https://en.wikipedia.org/wiki/ASCII_art

 

Storing Images and Sound

Starter

Storing Images

Storing Sound

Discussion Questions

Discuss in pairs / groups or as part of a class discussion

1. Sound and Images also need to be converted into binary in order for a computer to process them so that they can be seen on our screen. How do you think it works for Video? See if you can explain it in your own words!

Main Lesson Tasks

1. Open Microsoft Word and explain, in your own words, and using a maximum of 2 lines, how Computers store numbers, text, images and sound. Your explanation needs to be to the point but accurate. How well can you summarise your learning?

2. Create a single slide of information that explains the above (using images from the Internet where appropriate). It should be suitable for a primary school audience (so it should be simple enough for a Year 5 or 6 to understand)

Extension: Add a section that explains Digital Video and how it works

Theory and Links

http://www.bbc.co.uk/education/guides/zpfdwmn/revision/2#

Do a little research on DIGITAL VIDEO and how it works. See if you can explain it in your own words, or add it to the presentation above: Here's the wikipedia link

https://en.wikipedia.org/wiki/Digital_video

Independent Learning

Find out more about Famous Computer Scientists

Use wikipedia for your research: Charles Babbage, Alan Turing and Conrad Zuse. Pick out the interesting facts and useful information that you will later put in your research presentation

End of topic task and assessment

You've learned a little more about how data is represented in computers. It's now time for you to show us what you've learned. 

You can either complete the e-portfolio question/answers OR complete the tasks below

1. Create a power point that explains WHAT A COMPUTER IS & BINARY to a 6 year old. Think about the language and images you will use to keep it simple. Extension: What is the largest number a computer can store/hold? Think carefully about your answer and explain it, using supporting research.

2. Create a powerpoint presentation (information point) that presents basic information (fun and facts) about the three computer scientists: Charles Babbage, Alan Turing and Conrad Zuse

3. What is ASCII? Write a short article /create a presentation/or create a video explaining what ASCII is.