Lesson video

Hi, I'm Rebecca, your computer teacher and I'm going to be teaching you all about data representation.

For this lesson you're going to need a pen and paper to write down any notes and answer any of the questions that I give you.

You're also going to need to make sure that you remove as many distractions as you possibly can so you can really focus this lesson.

When you've done all of that we can begin.

In this lesson, you will give examples of the use of representation and you'll explain how binary relates to two-state electrical signals.

Let's think right back to those really, really early days of storytelling in early cultures.

Think about the following questions.

Write down your answers using your pen and paper.

Pause the video while you have a think about them.

Let's take a look then.

So why was storytelling so important in early cultures? Well, first of all, it was part of communication of cultural, social and religious ideas.

Education.

If you listen to stories about things, you might actually learn something and social bonding as well, because there weren't many forms of entertainment in those days, there were no online streaming services and things like that.

So people would tell stories as part of the social bonding of an evening out and listening to things.

So what forms does it take? So narrative, music, dance, rock art as well.

So for example, with music, I know that in the very old times, because we didn't have books and things like that, people used to observe things like battles, for example, and they might come up with a song that said what happened in that battle and they would go around to different villages and repeat that same song to spread that message, whether it was accurate or not, who knows, but that's what happened as part of storytelling.

And then what are the limitations? So you had to be there to experience it.

So you needed to be at the forefront of that battle to know exactly what happened and you had to make up the story as well, or the song and then you had to go to a village and say what happened and the only way that message would then get spread around is if you travelled around to other villages saying that exact same story, but then, you know, some people might listen to that and make their own version of it or make a diluted version or the message could get lost over time and also, how can you trust it exactly what happened because you know, the natural storyteller could have made things up or made a King look more powerful than they are.

So there's all sorts of things that might have happened in those early stages of storytelling.

You then got writing.

So writing came next.

Why was the invention of writing so important? Why do you think? Well messages could be transmitted across long distances.

So once it'd been written down on a stone or some paper or anything, anything like that, and that message can be transported by horse and carriage, by ship, to all sorts of places.

So messages could, could be transmitted across long distances that could be stored for long periods of time as well and you could communicate with many more people because once that person has written it down, then they can pass that message around to lots of different people, but also they can get messages back as well that might also be written down and people could share their expertise.

So if somebody in one part of the country found a cure for something, then they could then spread the message through writing to other areas of the country to find a cure for that too, so that they could share their ideas.

So writing is just a means of representing something.

There can be many different ways of representing the same thing.

How is it possible for a shape to represent a word? Pause the video while you have a little think about that? Actually everyone has to agree on it.

It's all well and good somebody coming up with a coding system of different symbols, but if people haven't agreed on it and people aren't prepared to use it in their own writing, then it becomes pointless, doesn't it? So everyone that uses it has to agree on a shared meaning for each of those symbols.

We use symbols to represent many things.

Can you think of some examples? Pause the video while you have a think about that.

Here's some examples that I've come up with then.

So letters of the alphabet, that's quite an obvious one.

Digits.

So all of your numbers.

One, two, three.

Mathematical operations as well.

Such as using that plus symbol for addition, instead of writing addition or add a musical notes that they symbolise different sounds, sign language for the letters of the alphabet and words and road signs as well.

So if you were walking down a road and it said, children crossing at this junction, then it'd be much harder for you to understand that, than just looking at the symbol for it, but you can't have that symbol without that shared agreement of what that symbol actually needs.

Computers are good at storing numbers, we'll find out why later.

Programmes, text, numbers, images, sound, are all represented in a computer using numbers.

We just need to agree on a coding system.

For example, 65 means a, but they got data and instructions.

Necessity is the mother of invention.

The invention of computers allowed us to perform calculations more quickly, accurately and efficiently than people can.

What do you think the components are for calculation? So look at that one, five times 12, what are the components of that calculation there? Pause the video while you have a little think about that.

Well, you've got data and you've got instructions.

So first of all, you've got five and 12, which are pieces of data And then you've got an extra instruction for what to do with those two pieces of data.

So you've got that X symbol, which means to multiply and it's an operation and it's to perform that instruction.

So do five times 12, that's your instruction there? How can we communicate our instructions to a computer? Well, by writing or running programmes.

How can we communicate data to a computer? By entering or loading values? What I want you to do is take what you know about data and instructions and just what you've thought about it so far.

So don't worry too much if you get this wrong, but what I want you to do is have a look at this recipe for a spongecake.

And I want you to see if you can pick out or what's the data, what's the instructions.

And there is an example on there to get you started if you're not quite sure as well.

So pick out five pieces of data and five instructions.

Pause the video while you do that and come back when you're done.

Let's take a look at those solutions then.

So first of all, thinking about the data that was in that recipe.

Now data, when it's on its own, it has no meaning.

So if you just saw, for example, 200 degrees C, you'd know is a bit of data or is probably something to do with the temperature, but you wouldn't know what to do with it.

It would have no meaning.

So anything in there that you can pick out that on it's own would have no meaning, it's probably going to be data.

So take a look at that list there where I've highlighted and see if you've got that right with your five that you picked out.

Let's look at instructions then.

So instructions are given instructions or directions to somebody to carry out or something.

Now so you've got things like preheat the oven, put this in a bowl, mix it, put it in the oven and leave it to cool.

All of those things are instructions for somebody to actually carry out or something.

So take a look at that list and see if you've got any of those from your five that you picked out.

I'm going to think a little bit more now about instructions and how they might be represented in computers.

So how many states can a switch or a bulb be in? Think about it? Well, the conventional bulb and conventional switch can only really be in two states, on and off.

So these states could also be called true for on and false for off or a one for on and a zero for off.

Anything that can be in two states is called binary.

Think about how you could communicate a message to a friend in a different location using it's two state system.

So it could be a light being on and off or a sound being on or off that kind of thing.

You might like to use lights, sound, electricity or something else.

You could think of other ways.

How could you communicate a short message to a friend? Pause the video while you have a think about that.

Now you could have come up with absolutely anything then, but what you could have done is something like with a torch where you flashing it on and off, you could have used, you could have thought maybe something like Morse code, cause the road using Morse code out there, which has got different light pauses or sound pulses for different letters of the alphabet.

So you could send it that way.

You'd have to do it letter by letter though 'cause it'd be very difficult to do a whole word just with a couple of flashes of a bulb, wouldn't it? That'd be quite tricky.

So I'd be interested to see what you came up with there.

Maybe that's something that you could share later on, but there's lots of different ways that you could communicate using that two-state system.

If you have more bulbs, you can represent more things.

So let's say we've got two bulbs.

How many combinations are there for a group of two light bulbs? So how many ons and off or on off, on, on, all those things, how many combinations can you think of? Pause the video while you have a think about that? Well it's actually four, cause you can have off, off, off, on, on, off on, on.

Those are the only combinations that you can have with those two bulbs that you've got.

In computers, transistors are used instead of these bulbs, transistors are tiny electronic switches.

These ones and zeros are actually the basis of a counting system called binary.

We will learn more about this in lesson two.

So that was your introduction into data representation and just starting to think about the history of where it all my come and why we need it and all that.

And then when we look at lesson two, you'll start to see, well, how this actually works with computers.

How did we get it to represent all of those things with a computer? So you'll find more out about that in lesson two.

Now what you've learned today, it'd be great if you could share that and if you'd like to, please ask your parent or carers permission to share your work on Instagram, Facebook, or Twitter, tagging @OakNational and #LearnwithOak.

So maybe you came up with a really funky idea for sharing or communicating with our two state system across a long distance with a friend.

Maybe you've thought about that and you've come up with a really cool idea and you could share that.

So you can get your parent or carer to do that for you Cause we'd really love to know.

Now that's the end of the lesson.

I'm really looking forward to doing lesson two with you very.