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

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

'Placemat consensus' Kagan structure

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.

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.

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

Next Steps

• 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.