Why Computing Unplugged?

Can you have computing lessons without computers, and would that be a good thing?

I used to liken the difference between Computer Science and ICT to the difference between architects and bricklayers; the existence of the latter is a consequence of the former, and it's also the role of one to implement the more conceptual ideas of the other. I was never entirely happy with that analogy, though, because there are also pay and status connotations that I hadn't intended.

Since Computing replaced ICT in the 2014 National Curriculum I've changed the way I think about the difference. One of the myths that has developed is that computer science is a niche subject only suited to those hoping to work in the software industry, while ICT is better-suited to the wider population. Nothing could be further from the truth, of course – the opposite is actually the case. The type of ICT taught in schools is really a vocational subject for students destined for desk-based, administration-type jobs, whereas computer science is for everyone.

People search for, and sort, things, plan routes, apply logic, etc., in all kinds of contexts that don't require a computer. Algorithms are not just for programmers, they're also for Chinese postmen and travelling salesmen (to name two of the most famous problems in Computer science).

Nothing illustrates this point better than the existence of "Computing Unplugged". While it's perfectly possible to demonstrate key Computer science techniques without using a computer, the same is not true of ICT. You never hear about "Spreadsheets Unplugged", or "PowerPoint Unplugged", for example.

Undertaking activities away from the computer not only shows that computer science isn't just about computers, and can be relevant to manual or off-line tasks, but it also helps to break the link between Computing and "playing" on the computers – it makes Computing look like the other subjects and enables us to practise our traditional "teaching" skills.

Sorting algorithms are a computer science staple, but physical items also need sorting. One of one of my favourite unplugged activities, therefore, is sorting. Anyone with a collection of records or books might have wanted to put them in order, but what's the quickest way? What about bigger sorting tasks?

When I first started teaching, we still hand-wrote reports with a pen. We completed an A4 sheet per subject per student, and put them in a tray in the staffroom for tutors to collate. Not only were tutors supposed to arrange the reports by student, but we were also supposed to sort the subjects into alphabetical order of name. A colleague was complaining one day that it had taken her ages to sort them, with the sheets spread out around her dining room, but I'd done it all in a ten-minute tutor period with the help of the students. I'd used an efficient parallel sorting algorithm and she hadn't. No computers were involved.

In their book, Algorithms To Live By, Brian Christian and Tom Griffiths go one step further and say that Computer science principles are not only useful for sorting our CDs, but that thinking like a computer scientist can help with the big decisions. Computer science is all about coping with limitation, just like life. PowerPoint can't help you with that.

In Finland, students routinely learn about computer science without computers. Computing principles can be applied in a variety of contexts – they learn about algorithms, for example, through knitting, dancing and music (maybe you could try an unplugged version of the Twelve Days of Christmas activity?). Even software companies are applying their expertise in non-computing contexts – Microsoft is using its computer science expertise to try to cure cancer, for example.

I was recently invited by course leader Jonty Leese to a Subject Hub of Excellence (ShoE) day at the University of Warwick's Centre for Professional Education. ShoE days invite experts in their subjects to share knowledge and expertise with trainee teachers. This is a good opportunity for students to look beyond the narrow requirements of the National Curriculum for Computing and expand their repertoire of teaching techniques. It also helps them to develop an understanding of what Computing is, which something that experienced teachers converting from other subjects and going straight into teaching examination courses don't always get the time to do.

The majority of the ShoE day I attended was about computing without computers. Amongst the things we looked at were creating logic circuits from dominoes, sorting networks, and using a card trick to explain the concept of parity. Some of these examples will help students to visualise things like logic gates, or to understand concepts such as parity before applying them in a more technical context.

I particularly liked the card flip magic task – students aren't always aware of things such as loose connections, electrical interference and the importance of error-free transmission, but they can appreciate a good trick and how it works.

The essence of Computing is really "how things work", so I don't see why we can't also take lesson time to explain anything from any subject area – when my daughter was learning about the Romans in year 4, for example, we discussed an algorithm to turn numbers into Roman numerals. Similarly, when she had a year 6 Maths homework to find "perfect numbers", we also took the opportunity to think about and write an algorithm for working out whether a number was perfect.

Some topics lend themselves nicely to analogies and off-line examples, but you also need to take care not to make the examples too obscure. I made my Words of Wisdom page, for example, in an attempt to demonstrate to students the difference between validation and verification, but it turned out to be a bit too abstract for most of them.

Another consideration is whether the benefit gained from an unplugged activity is worth the time and effort it requires. Take this examples of a four-bit adder made of cardboard, for example. If computing principles can be (or even are mostly) applied in non-computing contexts, then Computing Unplugged can be an excellent way to get students to learn and apply them. Technical processes, such as addition or the fetch-execute cycle, are only done inside the computer and, in my opinion, are probably best kept there – just tell the students how they work and save the lesson time for tasks that enhance computational thinking.

One of the downsides of Computing Unplugged is that it does often require unusual and infrequently-used resources to implement – large sets of dominoes or sets of 36 double-sided cards, for example.

What I do is take some of the unplugged activities and plug them back in to create web-based resources, such as card flip magic and the sorting balance. This might seem to be a bit contradictory, but the students still see the concepts in a (simulated) non-computing context and the whole class is able to undertake the activity at the same time.

Teaching computing without computers also helps Computing teachers to practise more traditional teaching skills (as used in other subjects), and to develop confidence in discussing concepts and ideas, such as the deadly ancient maths problem that computer scientists love, away from the computer without a practical demonstration. Having a Computing lesson without computers isn't something to be afraid of - it's an opportunity for both you and your students.

If you're not sure where to start, the CS Unplugged web-site contains ideas and activities. If you're not quite ready to take the plunge with a whole lesson, why not discuss a traditional problem, such as the river-crossing puzzle or the Towers of Hanoi, or give a logic puzzle from a "brain teaser" book as a starter and see how it goes?

This blog originally appeared in the TES Subject Genius series in March 2017.