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Slide 1 Slide 2 Teachers Notes: *** Briefly introduce the learning objectives for this lesson “Today we will cover the differences between the Internet, Web and the Intranet. This will then lead to further detail about the Internet and understanding a methodology for communicating across the Internet, called packet switching. We will focus on the Web and Intranets in a different lesson.” Slide 3 Teachers Notes: *** Use this as a starter exercise to get students interested in the topic *** Get students to shout out what they do online *** Now introduce the idea that everything they do online might end – natural disaster etc. *** Get responses from students about how they might cope/their ideas about why this might happen Slide 4 Teachers Notes: *** Use this exercise to explain that circles can be used to represent the Internet, Web and Intranet. Click through the animations as appropriate: “The internet is the largest circle because it encapsulates and underpins everything else. The Web is the middle sized circle because you cannot have the Web without the Internet, it has to sit on top of it. The most visible part of the Web is the webpages you look at everyday.” *** Extra question to stretch students: “The Internet houses the Web and Intranet, but Intranet also exists externally... Why? Does anybody know?” >ANSWER: “The Intranet also exists externally because it can be used as a private network. For example, in an office environment. The Intranet is like a private Internet just for you.” “Imagine your own home, if you own a laptop you can probably see the devices of everyone else within the household – everyone on your wifi network. However, other people on the Internet from the outside will not be able to see this.” “We will cover the communication between the Internet and the Intranet in more detail in a later lesson, just accept this principle for now” Slide 5 Teachers Notes: *** Hand out Activity sheet 1. Give Students 5-6 minutes to go through and fill in the gaps. *** Spend another 4-5 minutes going through answers on next 3 slides.... Slide 6 Teachers Notes: *** These slides help the teacher to talk through the answers to the filling in the gaps exercise. Slide 7 Teachers Notes: *** These slides help the teacher to talk through the answers to the filling in the gaps exercise. Slide 8 Teachers Notes: *** These slides help the teacher to talk through the answers to the filling in the gaps exercise. Slide 9 Teachers Notes: “Today we will be focusing on the Internet and how communication across the Internet is enabled”. Slide 10 Teachers Notes: “Protocols are a set of rules that enable computers to communicate with each other. Transmission Control Protocols and Internet Protocols, also known as TCP/IP. They are employed for communicating across the Internet”. Slide 11 Teachers Notes: “For now, you only need to know a quick explanation of these protocols. TCP is the underlying layer of the Internet. It is responsible for ensuring the delivery of the information. IP is responsible for providing logical addresses for routing the information. We will be covering this in further detail later on in this lesson” Slide 12 Teachers Notes: “To transfer information across the Internet, you send it through the networks. To accomplish this, the Information is broken up into what is known as IP Packets. IP packets are the “items” that are transferred across the networks. The diagram illustrates what the Packets contains: - As we can see it is broken up into two sections, a header and the actual information. - The header contains an address for both the source of the information and destination address that the information must be sent to. - It also carries the TCP information which includes the number packet it is and how many packets it is related to. - The Actual Data is the information to be sent” Slide 13 Teachers Notes: “So now we know the foundations for communicating across the internet involve: - Protocols: which are a set of rules - TCP/IP: are protocols used for communicating across the internet. They are responsible for delivering the information and providing addresses - Information to be transferred are initially broken into IP Packets. This contains the TCP/IP information as well as the actual data. ***Offer a minute for questions Slide 14 *** This slide is used to introduce the next section of the lesson “Now we will look at packet switching...” Slide 15 Teachers Notes: “Before we get into the technical details of Packet Switching, I want you all to think about when you send a letter in the Post. What is the process?” *** Give 2 minutes for students to call out answers Slide 16 Teachers Notes: “These are the main points of sending a letter. You write it, wrap it up in a envelope, add the destination address, hand over to the post box for the post men and sorting office to deal with, and then it is finally delivered to the person it is for.” Slide 17 Teachers Notes: *** Give 6-8 minutes for students to organise into groups and from the post office steps work out the possible packet switching steps using the slips from the Activity Resources – Activity 2 *** Give 2-4 minutes to discuss answers...hand out answer sheet >Answers are found in Handouts – Answers for Activity2 Slide 18 Teachers Notes: “We are now going to carry out a class activity to demonstrate the basics of Packet Switching. The Post Office Analogy is there to help you understand how it is possible”. *** Activity 3 -1: Use materials from Actvity_3ab.docx and Activity_3_Markers.docx *** If desks are in a grid layout, get all students to stand up at their desk. Otherwise, bring all/some student out into an open part of the classroom and arrange in a grid pattern. Ideally the grid should be a minimum of 3 rows and 4 students per row. *** The Start (A) and End (B) points for activities are opposite corners of the grid (one front corner, one back corner; issue them the appropriately lettered sheets). During this and following activities, if time and behaviour of the class allows, consider moving the A & B points around the grid so that more people get involved – they don’t have to be at the corners. *** Now show the next slide, which will illustrate how the activity will work. Slide 19 Teachers Notes: *** Click through this slide to illustrate the basic principle of packet switching Slide 20 Teachers Notes: *** Running activity 3-1. *** To start, label two students as A & B, get them to hold up their marker pages so everyone can see who they are. Issue the ‘file’ paper to A. Get A to pass it to any person close to them, in the general direction of B. Repeat the process until the paper arrives at B. Get B to hold up the file sheet when it arrives. *** Once the file arrives at B, show the next slide. Slide 21 Teachers Notes: “This slide summarises what has just happened.” *** Prompt reflection: ask students about what they have just done. Check that they see the document can take different routes across the network and still get to the correct end-point Slide 22 Teachers Notes: *** Activity 3-2: Re-use materials from Activity_3ab.docx and Activity_3 _Markers.docx (*** Op/on: before continuing, to get more people involved in larger classes, switch the A and B markers to different corners of the class from those used in the first run.) *** Now tell the students you are about to ‘switch off’ some of the servers in the network. Select about a third of the students, telling anyone you select to fold their arms, to indicate they are no longer receiving messages. Note: choose carefully make sure you still leave a path from A to B, but don’t just leave the most direct path. You want to show how the message can travel around ‘dead’ parts of the network. *** Re-run the previous activity *** Reflection: ask the class how the delivery of the note has changed: - Did the missing servers affect delivery of the message? - What does this tell us about resilience in the network? - How many different paths are needed between A and B in order to get delivery of of the message? >ANSWER: One! Slide 23 Teachers Notes: *** Summarise: run PowerPoint to show the sort of scenario just practised in the last activity. *** Sum up learning points: - the document can pass though many servers as it crosses the network - the document can take one of many routes - the document’s route can alter to allow for gaps appearing in the network - as long as one route is open the message can get through, even if not the shortest route Slide 24 Teachers Notes: *** Activity 3-3: Use materials from Ativity_3c.docx and re-use those from Activity_3_Markers.docx (*** Op/on: before continuing, to get more people involved in larger classes, switch the A and B markers to different corners of the class from those used in the first run.) (*** Op/on: if class size/behaviour allows, materials are provided to add new start/ end point C and D. Resources are marked so A/B and C/D notes route separately, making it possible to leave out the C/D op/on without affecting the main activity. Adding the extra route increases interactivity but may get chaotic if the class is large or unruly.) *** Each ‘message’ is now a series of 3 data packets (separate slips of paper). The packets all show their start/destination, packet number in the sequence and total number of packets in the sequence: e.g. From A to B, 1 of 3 (i.e. first of 3 total packets in the message). There is a message from A to B, B to A and optionally C to D and D to C. *** Give each start point (A, B, optionally C and D) their message packets. Tell these Slide 25 Teachers Notes: *** Summarise: run PowerPoint to show the sort of scenario just practised in the last activity. *** Summary: - observe how the packets may arrive out of order - that information in the packets lists the overall number in the message - that information in the packets lists which sequential number they are within the message. *** Confirm students understand how packet numbering helps reassemble the message and ensure it is complete (all the packets present and in the right order). Slide 26 Teachers Notes: *** OPTIONAL: Activity 3-4: use materials from Activity_3d.docx docx and re-use those from Activity_3_Markers.docx *** Time-To-Live (TTL) is explained on the next slide. As class sizes may vary, the teacher must decide on a TTL number and write it on each packet note. Work out the shortest route from A to B (opposite corners of the network) and add 2. Thus if the distance is 4 ‘hops’ set TTL to 6. This ensures any direct route packets will arrive whilst those using longer routes may time out. Slide 27 Teachers Notes: “The server getting a zero TTL packet sends an ICMP (Internet Control Message Protocol) type 11 (Time Exceeded) causing the originating server to resend that packet. Only that packet is resent, not the whole message. This allows packets to expire individually.” *** Activity: use the same layout and A/B start and end points in opposite corners (potentially change around the corners again). During this exercise all students need to have a pen. *** In this activity, A should pass packets one at a time - do not pass the next one until the previous one has got to the destination, or expired. Give the 4 packets to A. Instruct the group to pass the first packet from A to B, using the shortest (most direct) path. Wait until the packet has arrived before issuing the second packet, which should be routed around the outside of the grid (to ensure it expires). Lastly, send the third and fourth packets allowing the students to use any path they like. *** When passing a packet, the student should subtract 1 from the TTL, cross that number out and pass it on. If the TTL is now zero the student should retain the packet and hold it up for all to see. Slide 28 Teachers Notes: ***Summarise: run the PowerPoint to show the sort of scenario just practised in the last activity. The animation includes a packet expiring and a new one being sent, click through it as appropriate to activate the animation. Slide 29 Teachers Notes: “So what is the name of the addresses the packets use? ...IP Addresses. These addresses are unique, and act as a label assigned to each device in a computer network that uses the Internet Protocol. Question: Does anyone know what is the most common form of IP Address and what is the newer IP Address?” ***Give students 1/2 minutes to volunteer an answer. > ANSWER: The most common form of an IP address is known as IPv4. Newer form is IPv6....We’ll cover IPv6 in a later lesson Slide 30 Teachers Notes: “A bit of information about IPv4..... - It is the most common IP - There are 7 billion people on Earth, but IPv4 only offered about 4.3 billion IP addresses. - As it is limited with number of IP addresses it offers, IPv6 will be the improvement” ***Reference for stats: hhp://www.icann.org/en/about/learning/beginnersguides/ip-addresses-beginners- guide-04mar11-en.pdf Slide 31 Teachers notes: “IPv4 is made up of 32-bits, also known as 4 bytes. This means that the address can only store 2^32 different values (this is binary, to be covered at a later date). “ Slide 32 Teachers Notes: “Over to you...If 32 bits = 4 bytes, how many bytes are there in 1 byte? “ ****Give students 2 minutes to discuss and work out an answer > ANSWER: 8 bites = 1 byte Slide 33 Teachers Notes: “Here’s a fun fact for you....half a byte (which is 4 bits) is known as a Nibble!” Slide 34 Teachers Notes: “The IP Addresses are broken up into four ‘chunks’. Each of these chunks consists of number between 0 and 255, and represents 1 byte. IP addresses are broken up into four ‘chunks’, each of which can range from 0 to 255 and representing 1 byte”. Slide 35 Teachers Notes: “The first two chunks represent the network identifier. This enables you to identify the network the device is a part of, for example this school network or your home local network. The second two represent the host identifier. This is the actual node on that network, for example your computer, my computer”. Slide 36 Teachers Notes: “Here are a few examples of IP addresses. Work in pairs to decide whether each set of IP addresses are on the same network or not”. *** Give students a minute to work out the answer for each question. For each question get students to vote what they believe is the correct the answer (hands up for yes, hands up for no). Then reveal correct answer on the next slides. Slide 37 Teachers Notes: > 1: 126.203.123.123 and 126.203.100.100 ANSWER: Yes > 2: 126.203.123.123 and 155.155.120.122 ANSWER: No > 3: 126.203.97.54 and 126.203.123.123 ANSWER: Yes Slide 38 Teachers Notes: “To wrap up what we have covered today, I would like you all to individually write 4 or 5 points that you have learnt from todays lesson” *** Give students 5 minutes to write bullet points of what they have learnt *** Spend 5/6 minutes asking students to volunteer points and write on White Board forming a mind map summary for students to visualise before they leave *** Anything important missed, go to next slide.... Slide 39 Teachers notes: “These are the few summary points you should take away with you as well as the points we have just collated onto the mind map... We know the main differences between the Internet, Web and Intranet are that the Internet is the foundation, the web uses the Internet to work, and Intranets are private networks. Communicating across the Internet involves protocols (TCP and IP) and information is broken into IP Packets. The methodology employed for communicating is called Packet Switching.” Slide 40 Teachers Notes: “IP addresses are used to identify a device on a network, using a common form known as IPv4. These IP addresses are made up for four chunks, making up 32-bits. The first two chunks are known as the network identifier, and the latter two chunks are the host identifier.” ***Give hand out key_terms.docx Slide 41 ***Ask for Questions