1. Computer Networks – the Internet
Week 2
Lesson 1
Computer Networks – the Internet

2. Computer Networks – the Internet
This lesson, we’ll be investigating the highlighted questions …
How does the internet work?
How does data get from one computer to another?
How do s send?
How does the data/ s know where to go?
How do web searches work?

3.
This map from shows every device connected to the internet around the globe at a particular moment in time. The map was created by sending a ping request to every IP address on the internet.
Eastern USA and Europe glow a deep red due to their high levels of internet connectivity, however the map also gives us an insight into internet usage in the developing world. The east coast of South America and India both have a high number of internet-connected devices, as do Thailand and Indonesia. There is even a little dot right in the middle of Greenland – a research station perhaps?
Interestingly it actually took more time to make the actual map than collect the data. ‘It took less than five hours to gather the data, and another 12 hours or so to generate the map image’ says its creator.

4. Starter – true or false?
The internet is the same as the world wide web
Bill Gates did not invent the internet
Everything you read on the internet is true
In China, sites like Twitter, Facebook and Google are blocked or severely restricted

5. In today’s lesson: Lesson Objectives
Develop an understanding of how the internet works
Understand the difference between the internet and the www
Understand how we connect to the internet and how the internet itself is connected
Success Criteria
ALL: Explain the difference between the internet and the world wide web. State at least one way we can connect to the internet.
MOST: Give a simple explanation using some key terms of how the internet works. Describe a number of different ways of connecting to the internet.
SOME: Successfully use key terms to explain how the internet works. Evaluate the different ways of connecting to the internet.

6. Literacy -Today’s key wordsIP
address
Internet
ISP
DNS
URL
www
HTML

7. What is the internet?
The global computer network called the internet is part of our everyday lives at home and at school.
The internet is made up of millions of computers all over the world that are digitally connected to each other by cable, fibre or wireless links.
Mot of us use the internet daily to browse websites, communicate with people, download pictures and videos, listen to music or do lots of other amazing things. But where is all of this coming from?

8. What is the WWW?
Many people think that the internet and the world wide web are the same thing. They are closely linked, but they are very different systems.
The world wide web (‘www’ or ‘web’ for short) is a collection of webpages found on this network of computers. Your web browser uses the internet to access the web.
The www was invented in 1989 by an English scientist called Tim Berners-Lee who was trying to find a way to make use of the internet, which already existed, so that scientists could easily share the data from their experiments.

9. So what’s a website?
A website is just a load of files saved on a hard disk, files like your movies, music, or pictures. However, there is one part that is unique for websites: they include computer code called HTML.
Web browsers like Internet Explorer are designed to understand this code, follow its instructions, and present these files that your website is made of, exactly the way you want.
As with every file, we need to store HTML files somewhere on a hard disk. For the Internet, we use special, powerful computers called servers. They don't have a screen, mouse or a keyboard, because their main purpose is to store data and serve it. That's why they're called servers -- because they serve you data.

11. Internet - the Basics Learning Check …
On your whiteboard, choose the correct word for the following definitions
Internet www website server
A LOT of files saved on a hard disk
A collection of webpages
special, powerful computers
the global computer network

12. James May: an introduction to the internet
But have you ever thought about wondered how the internet works? Here’s James May to explain it all to us!!!

13. An alternative journey round the internet
If that was all too fast, here are the PC Ninjas to take you through it in a different way…..

21. Key terms On your whiteboard:
Learning Check … what do these acronyms mean?
DNS URL ISP IP address
The company who provide your internet
The address of your device on a network
Converts the text based addresses to IP addresses
A web address

22. How are we connected to the internet?
Depending on your ISP, your broadband internet connection might be by:
Copper telephone cables
Fibre optic (not available everywhere, but faster than cables)
You can also connect to the internet through 3G/4G and Wi-Fi (but that is also connected to the internet with cables somewhere!)
We download more than we upload, so providers of internet have adjust the capacity so there is more capacity for downloading and less for uploading.

23. It’s not enough to have each machine connected …
It’s not enough to have each machine connected ….the continents are connected under the sea
Map is a link, interactive when you’re on the site.

24. Around the world with underwater cables

25. What to do now
Make a new folder in your work area called Computer Networks if you didn’t do so last lesson
Log into Moodle
Go to ICT & Computing > Year 8 > Digital Networks > Week 2
Download to your documents the worksheet called Week 2 How the internet works (not to downloads, put it in your newly created folder!)
Open it and complete, save and print it.

26. Plenary – define today’s key wordsIP
address
Internet
ISP
DNS
URL
www
HTML

27. Computer Networks – How does the internet know where to go?
Week 2
Lesson 2
Computer Networks – How does the internet know where to go?

28. Computer Networks – the Internet
This lesson, we’ll be investigating the highlighted question …
How does the internet work?
How does data get from one computer to another?
How do s send?
How does the data/ s know where to go?
How do web searches work?

30. Literacy -Today’s key wordsIP
address
Internet
ISP
MAC
address IP
Trace
Router

31. In today’s lesson: Lesson Objectives
Understand how IP addresses are used by networks/the internet
Understand the difference between IP and MAC addresses
Success Criteria
ALL: Successfully explain the purpose of an IP address and a MAC address
MOST: Successfully explain why IP and MAC addresses are needed, and what an IP address can tell you
SOME: Successfully explain the difference between IP and MAC addresses and different types of IP addresses and when these are used

32. What are we learning today?
Last lesson, we started to learn about how the internet actually works and how the world’s computers are connected
Today we’re going to look in more detail at the route data takes when it is transferred around the world and how it knows where to go.
What can you remember from last week?

33. Starter - recap

34. Why do we need IP addresses?
IP addresses are basically like an address system for the internet. Any device connected to it needs an address.
We need IP addresses to identify devices on networks, either the local network such as within your home, or on the internet.
We also need IP addresses to identify the computers – the servers – where websites are hosted.
When the website was first created, all you needed was a computer’s IP address to connect to it and look at one of its web pages – but this means you’d need to remember them all!! For example, to get onto Google you’d need to remember:

35. What has an IP address?
Each device on a local network is assigned a private IP address which is only used with the local network eg within school, your home, an office
When you access the internet, all the devices on the LAN use one public IP address that is assigned to your modem-router by the ISP.
Servers which host websites have to have an IP address that doesn’t change so they can be found easily through hyperlinks.

36. What does all this “look” like?
Your device’s IP address is likely a private IP address, probably starting with — is a range of IP addresses specially allocated to private networks.
Private IP address
Private IP address
Internet
Private IP address
Private IP address
Public IP address from ISP
ISP

37. How do you find your IP address?
You can find your private IP address by using the network tools on your operating system (or the command line interface if you know what you are doing!)
You can find your public IP address very easily using an online website

38. What does the IP address tell you or anyone else who looks at it?
Your public IP address is like an actual address for your internet connection
It gives away limited information about you and the device you are using to connect to the internet.

39. Concerned about privacy?
Using your IP address, it is possible to establish your rough location, possibly your neighbourhood as latitude/longitude coordinates are given, the ISP you use, the operating system, how often you (or someone else sharing your router) visit a website.
Most home Internet accounts use a dynamic IP address, which your ISP changes from time to time so using it as an ‘address’ won’t always be reliable.
If you take your device to a coffee shop for example and use their Wi-Fi, you'll have a different IP address there (and public network security issues to consider).
Tracking/tracing IP addresses can be useful to crime prevention or detection! Think about how online predators may be tracked down….

40. MAC address (Media Access Control address)
A IP address assigned to a device can be changed easily.
But there is an address assigned to every Network Interface Card inside the device (the card inside your device that connects to a network) which is permanent and cannot be changed.
This is called the MAC address
This is used by your router to give your device its private IP address. These obviously have to be different for each device on the network otherwise there would be confusion!

41. MAC Addresses

42. IP ADDRESSES Learning Check … On your whiteboard,
Why do we need IP addresses?
Which type of IP address is given to a device in your home?
Which type of IP address is given to your router by your ISP?
What type of address does each device have that cannot be changed?
What does an IP address tell you?

43. Find an IP address
There are loads of websites online to find the IP address of your computer or the host computers of websites. Here’s one to try:
Then you can find out extra geographical information about that site using this website:

44. IP address trace
It is possible to trace the route taken from one computer to another, using the IP addresses of all the computers that data is passed to along the way.
This will show you the global journey from your computer to the computer you are connecting to.
Use the proxy trace to follow the route taken by a message from your computer to other websites

45. IP address trace
The proxy trace may not work in school, may have to use the host trace.
When you’ve traced the data, look at how many hops to get to the website.
If you run the trace again, the number might vary.
Routers will send data by the fastest route.
There are some sites with no details on them - some routers give less information to protect their security and prevent them being hacked

46. What to do now
Make a new folder in your work area called Computer Networks if you didn’t do so last lesson!
Log into Moodle
Go to ICT & Computing > Year 8 > Digital Networks > Week 2
Download to your documents the worksheet called Week 2 IP Addresses (not to downloads, put it in your folder!)
Open it and complete the activities, save and print.

47. Plenary
Think about the possible implications of your actions on the internet.
What if someone thinks they have broken the law on a website with a French domain name (eg but the server storing the website is actually in China – which country would you have broken the law in? France, China? Both? Or all countries that the data has travelled through?