# Lesson video

In progress...

Hi, I'm Allen Heard.

And this is the Computer Networks unit.

This is lesson one of six, and this one's about computer networks and protocols.

Today you will need a pen and paper or something to write with and something to write on.

So if you need those, you can pause the video and go and grab them and then pop back.

And when you're ready, we can crack on.

So in this lesson, we'll define the computer network.

Explain how data is transmitted, define what a protocol is, and we'll try and come up with some non-networking related protocols too.

Well, the first thing to think about is this question, really big question this one, how many devices are connected to the internet? So how many devices do you think in the whole of the world are connected to the internet right now? This is where you'll need your pen and paper.

So have a think, pause the video and when you've written a number down, come back and we'll take a look at how you got on.

So how many devices do you think are connected to the internet? Hundreds, thousands, hundreds of thousands, millions.

Got to be a big number, hasn't it? Okay, well, I'm not going to tell you whether you're right or wrong now, you can wait until a little bit later on.

So let's talk about computer networks.

What is a network? Well, a network is when two or more computers are connected together so that they can communicate.

So if you think about the kinds of things that we have around us, that can communicate with each other.

I might have some tablets in the home.

I have some mobile phones or what else could we have games consoles, they've computers that can be connected to the internet.

So when two or more of those are connected together, then you have a network.

So thinking about the things we have, that we think are connected to the internet or connected to each other, what common daily activities do you think use computer networks? So you need your pen and paper again.

I'll give you a few minutes to do this one.

Probably take you about three minutes, write down as many of those activities you can think of that you think make use of computer networks.

You can pause the video now and come back when you're done.

Okay, so how did you get along? I've listed some here of the typical things that you could have maybe in the morning, you might be playing some music on a Bluetooth speaker, you could be asking your smart speaker for the weather forecast, for instance.

I sometimes ask you what the weather is going to be like.

So I know whether to wear a t-shirt or not.

And you could also control your heating via an app on your phone if you wanted to.

So if you're out and about, and you realise you might get a little bit cold, you could set the heating to come on while you're away, so that be nice and warm when you get back.

During the day, you could be logging onto a PC like today for a computing lesson and come and see you see me teaching all about networks, or you could be looking at files stored on the school network, if you end up going back to school sometime soon, and hopefully you'll enjoy yourselves when you do.

Going back to school and looking at the files you've got stored on your network, you could be printing.

Printing something out again that uses a network.

If you're printing from the computer in your classroom to somewhere else with the printers are there in the same room or somewhere else that's using the network.

And then finally for the evening, you could be streaming a movie, TV show or playing online games.

All those things use computer networks.

So here's a task for you to do now.

I want you to imagine there are no computer networks, okay, and you need to send a message from the UK to Australia, but no computer networks exist.

So what methods would you use? What information would you need and would anyone else be involved in relaying the message? Okay, so you can pause the video, pop the information down on your paper and when you're done, you can resume the video.

Okay, now I've got another one for you, similar task, but now computer networks do exist.

So with your pen and paper, again, imagine you need to send a message from the UK to Australia and computer networks do exist.

So what methods would you use? What information would you need and who would be involved in relaying the message? So write those piece of information down, and when you're done, you can resume the video.

Okay, so let's take a look at without networks.

So probably, or hopefully you might have thought, you probably send a letter in the post.

I suppose you could take it by hand if you got on a boat and you rode all the way there, or you got on some kind of boat that was powered and you went all the way to Australia to deliver yourself.

Seems a little bit extreme to me, to be honest, however, it's possible.

And it's probably how they did it way back when.

But thankfully we have the postal service.

So we have post depots, but varying locations around the world, you pop it in the post box.

Someone comes to collect it.

They take it to a depot, they send it to another depot, somewhere further along the chain.

And this happens until whatever transportation methods have been required.

So for going on plane, for instance, landing get to another postal depot all the way until a postman delivers it to the address in Australia.

So the letters pass to these depots from one to another, until it reaches its destination.

With computer networks, thankfully we can send it via email.

And just as a letter doesn't go straight from your hand or your postbox straight to the recipient, the email doesn't travel straight from your machine down one cable straight into the recipient's computer.

It all happens similar to the postal depots I suppose, but instead of be postal depots, these would be computer servers.

So these mail servers would collect your letter.

It would get sent there and they would send it onto another one and then sent onto another one and then send it onto another one until it reaches its destination.

Now, obviously, if this was Australia, it wouldn't take anywhere near the amount of time it takes to send it by the mail, it would just happen pretty much instantaneously.

Okay, let's talk about protocols now.

A protocol is just a set of rules, okay.

So what protocol exists for meeting someone new, for instance, and is it the same in all countries? Well, in the UK, as we saw there we had a pair of handshaking, in the UK, it's generally accepted that we can smile say hello.

And sometimes we might feel a need to shake someone's hand, sometimes we might not.

In other cultures, people use different protocols to greet each other.

So for instance, in Japan they may bow, Inuits will rub noses and Tibetans will actually stick their tongue out.

So I guess it's really important that both parties involved in the communication know the rules, because if I went down the street and knocked on my neighbor's door and certainly when he answer the door, I just stick my tongue out at the guy.

I don't think he'd be too impressed.

And similarly, there is a little old lady who lives across the road, called Sandra, if I knocked on her door and she answered and I just started wildly rubbing noses.

I think I'd be in a bit of trouble.

She'd think I was a little bit strange.

But it's the same with computer networks, not that they rub noses, but both computers need to share the same understanding of how the communication is going to take place.

So that's what a protocol is.

It's a set of rules.

So what rules or protocols exist for email and web addresses.

So you should hopefully know what an email address looks like, and you should know a web address looks like, what is the web web address made up of? And what is an email address made up of? What rules would you have for our protocol for those two things? You'll need your pen and paper, so you can write them down what you think you know and resume the video when you've written them down.

Okay, so let's look at the protocols for email and web addresses.

So you should be able to recognise in an email address that they've all got the at symbol.

So at no matter what email address it is, it's always got to have one of those.

And email addresses must be unique.

So if you've ever tried to sign up for an email account and you might want to, you know, you can make them your own email address, it might have send this account has been taken, because they've obviously got to be unique so no two people can have the same email address.

With web addresses, they've always got HTTP colon forward slash forward slash at the front of them, sometimes followed by WWW, but not always.

And there again, they're unique and separated by dots, the different pieces of information.

So you can see an example there, thenational.

academy, which is where you're watching this lesson.

So you can see the information separated by dots.

So just thinking again, I mean, we've been talking about, devices on the internet and the rules for communication and then you got some examples earlier about things like smart speakers, what else did we think about, we thought about, streaming movies.

Okay, so let's think back to this again, how many devices are connected to the internet? We did this at the beginning and your number, maybe big, maybe small.

I'm not sure, but now is your chance to kind of have a little bit of a rethink.

Okay, I'm going to give you a chance to try and get close.

Don't normally give second chances, but we'll give one in this instance.

So let's have a little bit of a clue.

You've got somewhere around 8 billion people on the planet.

Okay, now, not necessarily every one of those have got a mobile phone, but if there's 8 billion people on the planet and we know we've got things like smart speakers, they're connected to the internet and we've got things like TVs that connected to the internet, we've got remote controls for heating on our phones and all that kind of thing.

Stream boxes for TV, for things like Netflix and so on.

So do you want to change your number or you are happy with what you got? Might you have put it too low, do you think, or did you really go astronomical and you put a really high number to start with? Okay, well, I'll give you an answer.

It's over 27 billion devices.

That's a lot of devices all connected to the internet at the same time.

Some of those are not necessarily for people to communicate with each other.

These devices just communicate with each other to provide us certain services.

By 2025 it's projected that there'd be about 75 billion devices.

So that's a really, really large, large number for the amount of devices that will be connected to the internet at any one time.

So hopefully you've enjoyed the introductory lesson to networks.

It was great to teach you all about devices connected to the internet and what a protocol is and how information might be transmitted across a network.

Hope to see you in less than two.

We'd love to see what kind of work you've been doing, and we'd like you to share it with Oak National.

It'd be really interesting to see how many devices you thought were connected to the internet.

And did you revise that number later on? Really interesting to find out.

I hope you enjoyed that.

See you next time.

Bye.