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Teaching how the internet works at KS2

12:36 Jamie Edmondson 1 Comments Category : , , , ,




As a Lead School for Computing, I was recently invited by Computing At School (CAS) to submit a case study highlighting best practice within the teaching of Computing. I though I would share a Year Four lesson that I taught recently, in which we explored the concept of how the internet works...

Background

The lesson is a Year Four lesson which covers the learning objective: ‘to understand how messages are passed along networks.’ The lesson covers the Key Stage 2 objective from the Computing Programme of Study, which states that pupils should be taught to; “understand computer networks including the internet; how they can provide multiple services, such as the world wide web; and the opportunities they offer for communication and collaboration.” The unit forms one of three Computer Science based units that the pupils study in Year Four. The lesson outlined here is lesson two of a six lesson unit, in which pupils ultimately make their own ebook about computer networks. The lesson builds on the work covered in lesson one, where pupils took part in a guided tour of the schools local-area network system and held a ‘question and answer session’ with the schools IT field technician. During the lesson, pupils take part in a practical, role-play activity, whereby they simulate a computer network system in action. In doing so, pupils are required to demonstrate an understanding of the different component parts of a wide-area network system (or 'WAN' for short).

Prior Learning

Although having not previously covered the concept of computer networks in any great detail, the pupils did bring some prior knowledge to the lesson, through the work that they covered in Unit 3.6 of our Computing scheme of work. Within this unit, pupils looked at how the internet works, particular focussing on the use of search engines. I was able to draw upon parts of this unit, by encouraging pupils to reflect on some of this prior knowledge.

 The Lesson

Introductory Task
Teaching strategies used: Paired talk, group work and class discussion.

I introduced the lesson by asking pupils to reflect on the previous weeks work, in which they were given a presentation by the schools IT field technician, followed by a guided tour and explanation of the schools network system. I asked pupils to look back at the notes that they had recorded during this time and instructed them to have a brief discussion with their partners, in order to recap what they had learnt. I then posed the following question:

“What is meant by a local-area network (LAN) and describe how a 'LAN' system works.” 

As a prompt for them to refer to, I also displayed this diagram of a LAN system...

diagram of a local-area network ('LAN') system

Then, using the Kagan cooperative learning structure ‘placemat consensus’, I asked them to jot down their initial thoughts by recording their ideas within their section of their group’s placemat. Pupils then worked together within their table groups, to record common responses in the middle of the mat. During this time, the Teaching Assistant supported a separate group with additional literacy needs, by helping them to record their ideas. I supervised the other groups as they completed this introductory task. After 10 minutes, I then called on one numbered pupil from each table, to feedback their groups final agreed definition of a local-area network ('LAN'). Then we all agreed on one final best definition and this was displayed on our working wall.

'Placemat consensus' Kagan structure
I then introduced pupils to the term ‘wide-area network’ ('WAN') and gave pupils time to discuss with their partners what they thought this referred to. In doing so, I encouraged pupils to use what knowledge they had acquired so far. After taking feedback, I then explained a wide-area network as typically consisting of two or more local-area networks ('LANs'). I explained how computers that are connected to a wide-area network are often connected through public networks, such as the telephone system or can also be connected through leased lines or satellites and that the largest WAN in existence is known as the internet. 
                      
        Main task: ‘How does packed switching work’?
Teaching strategies used: Direct instruction, explanation, modelling, concept mapping, whole class work and group work.

I then set about further developing pupils understanding of how network systems work, by introducing them to the process of ‘packet switching.’ First, I asked pupils to imagine that they had a data file (for example, an email or a document) that they needed to send to someone else. I explained that when people send files such as these, it isn’t sent as one document, but instead is broken up into lots of small 'data packets’ (for example, a 2MB file would be broken up into chunks of 512 bytes in size). I then went on to explain that before each packet is sent, it is given a 'header' containing the network IP address that it needs to arrive at and also details of the IP address from which it was sent. At this point, pupils were able to again draw upon some of the knowledge that they had acquired in lesson one (the IT field technician had explained what IP addresses were - i.e. a short sequence of numbers that uniquely identifies a computer, so that data can be sent to it). I then explained that the ‘header information’ also gives each packet a number and records how many packets the data was split into. I then asked pupils if they could remember where the school’s network switch was from the previous lesson and reminded them that the network switch’s job is to send ‘data packets’ to the computers connected within the network. 

The pupils then took part in the following whole class activity, which is outlined here…

First, I gave every 3 out of 4 pupils an ‘IP address card’ and 1 out of every 4 pupils a ‘switch’ card. Pupils given an IP address cards, were then also given three message slips each. I then asked pupils to sit on the table coinciding with the first number on their slip (for example, IP address 3.2 sat on table 3). I also ensured that there was one ‘switch’ on each table, as in the image below.
table arrangement
 IP address cards and 'switch' cards 
data card 
'router' card
Once all the pupils were sat in the correct place, I then explained that the person with the ‘switch’ card on each table would be acting as the ‘network switch’ and that the other children would be representing the computers (in essence, forming a small, local-area network within their table). I explained that the class as a whole would be representing the internet.
Next, I asked each ‘computer’ (i.e. every pupil with an IP address number), to think up a short message. Once ‘computers’ had composed their short message on individual whiteboards, I then instructed them to split up their message into three separate parts. I did this by first modelling how to write part of a message on each of the three separate slips, as in the image below.


I also instructed pupils to write the IP number of the recipient in the ‘To IP address’ field and their own IP number in the ‘From IP address’ field. Finally, pupils were instructed to write the ‘Data packet number’ (out of 3) and the actual ‘Data’ itself (i.e. the message) 

Once the data slips had been filled in, I then instructed ‘computers’ to pass these to the ‘switch’ on their table. ‘Switches’ were then instructed to sort these data slips into piles, by referencing the first digit of the IP address. To assist them, each 'switch’ was given a pack of envelopes, so they could sort and organise each pile of messages into separate ‘packets’. ‘Switches’ were then told to write the IP address of the intended recipient on the front of their envelope.

Once sorted into relevant piles, I explained that the next task was to pass each envelope to the relevant other ‘Switch’ on each table. Here, a few pupils, who had not been assigned a role (due to the logistics of the number of pupils in the class) played the part of ‘Routers’. Their job was to deliver these messages to the next intended 'Switch'.

Next, once switches had received all the data packets for their table, they were then instructed to pass these on to the intended recipients within their table.
Finally, recipients were then instructed to use the information presented within the ‘To IP address’ and ‘From IP address’ fields, to reassemble their message into the correct sequence. Once they had done this, they then wrote down their message on their sheet.

Plenary 
To conclude the lesson, I showed pupils a video modelling the process of what the pupils had just done, but from the perspective of connecting to a website hosted in America... 


    
As pupils were watching the video, I asked them to draw comparisons with the activity that they had just done. After watching, I emphasised the following points, in order to eradicate any misconceptions;
  1. IP addresses are much longer than the ones used in the activity they did. 
  2. The switch for the sending network hardly ever communicates directly with the switch for the destination network (instead, packets of data go through many different routers between the sender’s switch and the recipient’s switch).

Impact

Throughout the lesson, the pupils were engaged, motivated and on task. In particular, they responded really well to the practical, hands on activity covered within the main part of the lesson. This appealed to their preferred kinaesthetic style of learning. During the lesson, all pupils extended their prior knowledge of local-area network systems and were also able to extend this understanding in order to simulate the re-enactment of a wide-area network system. The plenary video provided a real ‘wow’ factor moment at the end of the lesson and pupils were able to clearly draw connections between what they had learnt to the concepts outlined within the video.

Next Steps

To make the lesson even better next time, I may make the following adjustments;
  • To ensure that each IP address receives a message, the main activity could be organised so that each IP address is matched up with another (for example, all the IP addresses starting with a '1' could write a message for all the IP addresses starting with a '2'). 
  • Within the main activity, I might ask each IP address to name themselves after a particular character in order to fit a particular topic/theme (for example, IP address 1.3 could represent ‘Harry Potter’s’ computer, IP address 1.4 could be ‘Hermione Granger’s’ computer etc.) These could be listed beforehand for pupils to see. Pupils could then choose a character and write their message as if it were an email message intended for them. 
  • To stretch the higher ability pupils, they could be given more than 3 message slips to make the activity more challenging. 
  • As an extension and if time permits, pupils could repeat the activity by responding to the messages they’ve received.
On the whole, I was really please with how the lesson went. The practical nature of the activity, ensured that pupils were fully engaged, in what otherwise could be quite a 'dry' concept. It also enabled them to extend their understanding of the main concepts that they had been introduced to within the previous weeks lesson.

If you would like to try out the lesson yourself, you can access all the resources used here on my TES page or here within my Pinterest page.

If you would like to subscribe to the online Computing curriculum that this lesson was taken from, you can do so here.

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