Unpacking networks

By Ben Hall. Posted

A role play of a large network of devices connected in a many-to-many structure

Originally published in Hello World 20: Systems and networks, Jan 2023. All information true at the time of original publishing.

Networking can be one of the most difficult concepts to teach in computing. Much of what takes place is hidden or invisible: switches and routers are usually tucked away in a cupboard, wires are routed through ceilings and under floors, and wireless connections cannot be seen. The speed and complexity of millions of bits of data travelling at the speed of light is also very difficult to comprehend, especially for primary-aged children.

To structure learning about networks, it is beneficial for learners to follow a semantic wave (see page 46 of The Big Book of Computing Pedagogy for more on semantic waves, helloworld.cc/bigbook). After introducing an abstract networking concept, educators can then make that learning more concrete by unpacking the concept and relating it to the real world.

Role play

You can begin by using role play. In its simplest form, a network is two or more devices connected together. One learner can play the role of computer one, and another the role of computer two. Connect them together by getting learners to hold either end of a piece of string. To simulate data moving, get them to pass an object, such as a keyring, along the piece of string to each other. This is the first part of networking unpacked: things flow between devices that are connected.

You can then create a larger network of devices connected in a many-to-many structure (see image). At this point, you will need to highlight that many-to-many connections are quite inefficient and messy! You can reinforce this by reassigning roles. In groups of about six, make one learner a switch and the remaining learners computers. Each ‘computer’ will hold a piece of string, and the ‘switch’ will sit in the middle holding the other ends of all the pieces of string. Now, to pass a message to another computer, a learner will pass it to the switch, who will then ‘switch’ the message to the right piece of string to get it to its destination.

You can make this model more complex by adding devices such as printers or servers, all linked to the switch. If you want to extend the analogy to the internet, you could join the groups of learners to each other by introducing routers. These will be between networks, joining one network to one or more other networks. You should then be able to get a message from one end of the classroom to another by passing it through all the various connections. This is a very accurate, albeit simplified, representation of what happens on computer networks.

To repack the semantic wave, remember to connect the activity back to a real computer network before showing learners the process happening on a network itself. Before you do this, you will probably have to address an alternative conception that the physical activity may have introduced. In reality, many devices on a network are not physically connected, as they are Wi-Fi-based. You can show learners a wireless access point and explain that the data is sent through the air to their devices, such as mobile phones. These devices are not physically connected to each other, but you can still communicate with other people by using them.

Now that learners understand the fundamental principles of networking, they will be able to apply their knowledge to more complex and larger-scale situations. The string activity is not just a simplified version of local networks, but also of the wider internet. In the case of the internet, though, the string is thousands of miles of fibre-optic cables on the ocean floor — still connections between computers, but on a much larger scale!



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