“Big church.” “Nice church.”

“Big church.” “Nice church.”

Typical comments perhaps from someone with few facts in their long term memory, when visiting a famous cathedral, according to blogger and primary teacher Solomon Kingsnorth in this tweet thread from 2018.

Kingsnorth suggests that with the benefit of a knowledge-rich curriculum, you might hear these comments instead: “Looks gothic, different to the baroque cathedrals I’ve seen.” or “I’m metres away from a tomb containing the heart of Richard the Lionheart. My own heart is racing.” Because as Kingsnorth explains: “To have facts in long-term memory is to have a private tour guide to the universe LIVING IN YOUR BRAIN, ready at a second’s notice to give you a plethora of information which will enrich your experience of everyday life.”

One might counter that the first person is still able to read a guidebook to learn about the cathedral, however the second person will still have the richer experience, because the guidebook will make more sense, its content triggering even more connections to existing knowledge which are recalled and enjoyed. Knowledge is both what we think with and think about according to English teacher and author David Didau, therefore more knowledge in long-term memory means richer life experiences.


I first encountered the idea that we “think with knowledge” in my second year of teaching (2017), when I first read “Why don’t students like school?” by cognitive scientist Daniel Willingham. Until then I had been a fan of constructivist thinking, very much beloved of Computer Science legend Seymour Papert, famous for the phrase “The role of the teacher is to create the conditions for invention rather than provide ready-made knowledge.” My attempts to replicate Papert’s alleged success with “learning through creating” were ineffective, however, which was unsurprising when I learned that “unguided or minimally guided learning is significantly less effective and efficient than guidance that is specifically designed to support the cognitive processing necessary for learning.” (Kirschner, Sweller and Clark).

Over the next year I read more on cognitive science and became convinced of its importance to my teaching practice. I moved schools from one where constructivist pedagogies were common, to a school which embraced “cognitive load theory” (CLT) including the illuminating notion that “understanding is remembering in disguise” (Willingham). The school values a knowledge curriculum too, and since joining my practice has developed considerably.

Back to our cathedral, and we can understand why the second visitor enjoyed a fuller experience if we listen to E.D. Hirsch who explained that “Learning builds on learning” and that existing knowledge acts as “mental Velcro” which allows new knowledge to stick to it. (Hirsch, 2000) Hirsch goes on to claim that “knowledge is the great equalizer, schools have … a responsibility to provide more equal life chances for all students [through transmission of knowledge]”.

Michael Young went further in 2014 to describe the types of knowledge that provide opportunities to succeed in life. Young (2014) explains that knowledge is powerful ‘if it predicts, if it explains, if it enables you to envisage alternatives’. Robbie Burns explains in his MA thesis (summarised in Impact here) how powerful knowledge gives “students the knowledge they need to go beyond their own experiences towards greater social mobility.” (Burns 2020).


I do believe that learning knowledge empowers our children to succeed in life and improve their life chances. But even if we sometimes fall short of that lofty aim of social justice, I also believe, despite the clunky nature of the phrase and it’s problematic origins, “the best that has been thought and said” is every child’s birthright. As Ben Newmark put it so eloquently in his book “Why Teach” and on his blog here: “We teach because … our children are the heirs of all that has gone before them and by teaching them well we gift them their birth right to the fruit of our civilizations”. Let’s give that gift, to the best of our abilities.


Passwords or pens: preparedness is a vital habit for life

I give sanctions for forgotten passwords. A C1 the first time and then a 15 minute detention for a second offence. Password resets are reasonably rare in my classroom as a result of this, and positive support for good password choices and habits – more on which later.

This tweet has 98 likes at time of writing, which means I am not alone in having trouble with passwords being “forgotten”.


In the tweet, like the above paragraph, I have put speech marks around “forgotten” because that’s the claim they make, yet often it’s not the case. Firstly, sometimes the error lies elsewhere – a mistyped username, for example. Students forget the username convention (how many letters of each name, what numeric prefix, whether we have included the hyphen or apostrophe in their name, something as a school we are not consistent about despite my best efforts), and therefore a password reset won’t help.

I find that this strategy works well:

  1. No password resets before the register. (This requires a DO NOW that either needs no computer use, or has an alternative activity that does. I have textbooks on the desks so they can pick one up and read about todays topic while I take the register). This rule gives the pupil more thinking time, and an incentive to remember the elusive password, and often they magically remember it, during this time.
  2. No password resets until I have watched their attempt to sign in. I often spot the error, such as a mistyped username. I also discover misconceptions here: we use Microsoft 365 and students often forget that if they have had their “365 password” reset, this will have synchronised to Windows also.
  3. If this support doesn’t result in a successful login, I will reset the password at the cost of a C1 and potential detention. I write the C1 and a note in their planner, and also get the student to take ownership of their error, by saying “I have forgotten my password”. I ensure they are disavowed of any notion that this just “happened to them” and that they made a mistake and must try harder. Passwords are, like a pen, exercise book or PE kit, a vital piece of school equipment and pupils must take responsibility for remembering it.

Good password choices

I get about one or two resets a week by this time in the year (December), out of over 300 students I see weekly. I think that’s a good rate, I know in the replies to my above tweet that other teachers have it worse. Maybe my September teaching and sanctions regime is working. In September’s first lesson I teach good password “hygiene”, basically:

  1. Choose a strong but memorable password. I insist on the adjective-noun-pad method, resulting in easy to remember but hard to guess combinations like Redgoose12 or Fluffyrat96.
  2. Write username and a password hint in your planner. A hint for Redgoose12$ might be r.g.phb$ (because BFF Phoebe lives at number 12).
  3. I give a second-lesson no-C1 grace period for forgetting passwords in Year 7 but remind them it will be a C1 next time.

I show this on the board to help with password choices, what would you choose from this list?



Whether it’s a pen, PE kit or password, if it’s an important piece of equipment, the pupils should get into the habit of coming to school with it. As shown above, once I have taught the necessary skills of choosing and remembering a password, sanctions are a vital extrinsic motivator to ensure they use those skills. Today it’s a pen or a password, tomorrow it will be (as I said on Twitter here) steel-toecapped boots, a security badge or, well, a password. We’re in the business of inculcating skills for life, so let’s get on with it.


HTTCS on tour – major update!

“You should do a book tour” said Allen Tsui on #caschat last night. I replied that I am doing a virtual tour! Scroll down for the evidence…


I recorded a series of YouTube videos with Craig ‘n’ Dave over the summer, the first of which is here. I then recorded the Learning Dust podcast with Andy Colley and Dave Leonard which is now live here.

“Unscripted” with Craig’n’Dave.

And my “CAS Inspire” podcast with Beverly Clark is now live here, alternative links here.

Also I have been busy with Edtech demonstrator work, delivering free training to schools via the United Learning Edtech Programme. If you need any help with Edtech: I can help as an official Edtech demonstrator, or with Computing: I can help as a CAS Master Teacher. Just reach out on Twitter @MrAHarrisonCS.


On not using mnemonics, and don’t get me started on crocodiles.

I’ve just seen another example of a mnemonic for remembering domain knowledge that reveals a potential lack of understanding of the subject matter, or a shortcoming in teacher pedagogy…

“To remember which binary shift does what, use this mnemonic: Lemon Meringue is Really Delicious – Left Multiply, Right Divide” (I have changed the mnemonic to protect the original poster).

I worry about any class learning this mnemonic as it suggests they are not being taught what binary shifts do, or why shifting multiplies or divides, and how this behaviour is exactly the same in any number base.

I teach binary by starting with place value and explaining how the places each have a value based on their position, which goes up by 2 each time as we move left, because we are in base 2, and show how this is exactly the same as in denary just with a different multiplier (10). When doing shifts I then do lots of worked examples in both denary and binary, and convert each binary result back to denary to illustrate the multiplying by 2 and dividing by 2 that is happening.


In this way, the binary number system becomes demystified – it’s just the same as base 10 just with different place values and a reduced symbol set (0 and 1). So they totally get that moving digits right (to the less significant places, the smaller column headings) makes a number smaller, and they understand that moving digits left (towards the more significant places, the larger column headings) makes it bigger.

Using a mnemonic suggests that the core concept of place value has not been taught or learned.

I feel the same about teaching greater than / less than by using “the crocodile eats the other number“, and about mnemonics like “rOm is nOn-volatile”. The < and > symbols are representations of growing and shrinking, the symbol is larger on one side than the other. Why add complexity with some notional crocodile? And ROM means “read-only memory” so it cannot be written to, so if it was volatile (lost its contents on power down) then it would be a pretty useless wafer of silicon as it would remain empty forever more. If they understand what ROM really is, and what volatile means* they cannot get this one wrong.

* I teach “volatile” with reference to Chemistry, where it means “easily evaporated”. If something evaporates it is lost, like the contents of volatile memory.


Relying on tricks can sometimes add complexity and confuse: One maths teacher told me that one of their students “got the greater than and less than symbols backward, because she believed the larger number would therefore be in the crocodile’s stomach after he ate it”.

Just teach the subject knowledge. Teach it well. And check for understanding. No crocodiles please.


Explanations matter.

Good explanations are vital to student understanding.

I pride myself on my explanations. Words are my forte (did you hear I wrote a book? 🙂 ) In my lessons I always explain the new material in a rigorous and deliberate manner, going back over tough concepts a few times, in a few ways, using analogies with familiar concepts, clearly enunciating any new terms and repeating them in different sentences so that the students get a feel for the new word and it’s meaning.

For example, protocols. I might start the topic of network protocols by explaining they are “rules for communication between computers, they make network communications work”.


I’ll then illuminate the concept of protocols by discussing the rituals people use when greeting a new person: they say hello, exchange names and use each other’s name when speaking, and so on. I then might say something like this:

“The rules of communication in polite society are a kind of protocol, a set of rules that make the interaction work. We follow a protocol because it makes everyone comfortable and helps communication be successful. The protocol tells us what to do when we meet people, and when we conduct a conversation. Establishing and following this protocol is important because it helps the conversation flow smoothly. Without any rules of communication which we call a protocol, meeting a new person and having a conversation with them would be quite difficult. Because both parties already know the protocol – the rules of communication – they can conduct a conversation with great success”.

I will then check for understanding with a few questions, using powerful questioning techniques from TLAC like “Wait Time”, “Right is Right” and “Cold Call” (unlike Ferris Bueller’s ineffective Economics teacher (see image).

I have so far used an analogy to introduce the concept of protocols in a familiar setting. I will then come back to discussing protocols in computer networks: being a set of rules for communication between computers that serve the same purpose – making communication successful – and in this way I have travelled a “Semantic Wave” to get the concept across, see this TeachComputing blog post for more on that.


But you will also note in my teaching narrative, I have used the word protocol no less than five times, in different contexts, ensuring students hear the phrases “follow a protocol”, “establish a protocol”, and “know a protocol”: it’s something to be established, known, and followed. They also know why: “helps communication be successful”.

Many teachers appear to be looking for that “magic lesson” which “drops the knowledge right into their heads from a PowerPoint slide”. Teachers: that magic lesson doesn’t exist but you don’t need it, you have all you need: your subject knowledge and a quiet class that listens to your explanations.


Exploring the Hinterland

There is great pedagogical value in exploring the hinterland with your students, as I explain in my article for Hello World magazine, issue 17 available as a free PDF here.

I shared a sneak preview of this article last month on this very blog. Now that it’s “out in the wild” it’s had some lovely reactions. Many schools are asking their teachers to add “cultural capital” to their teaching, and it’s a common misconception that this needs to be “bolted on” to the subject. Other conversations I’ve had reveal that many teachers think the “Issues and Impacts” or “Ethical, Cultural… Issues” topic in GCSE Computer Science is the only place you can teach cultural capital, after all it’s where we discuss the impact of tech on education and employment, the effects of eleectronic waste on the environment and so on.


My article (and for further reading, my book HTTCS) shows that there is cultural capital to be found across the curriculum, from linking Ada Lovelace to Byron and Mary Shelley, to Al-Khwarizmi’s influence in 9th C Baghdad, to the conflict between white settlers and native peoples in America’s west driving demand for the telegraph and eventually digital communications, cultural capital is everywhere in our subject. Read about it and share it with your students, your classroom will be enriched.


HTTCS on tour!

I’ve been a bit busy lately, hence the lack of tweets. I recorded a series of YouTube videos with Craig ‘n’ Dave over the summer, the first of which is here. I then recorded the Learning Dust podcast with Andy Colley and Dave Leonard which will soon appear here.

“Unscripted” with Craig’n’Dave.

And just now I recorded a “CAS Inspire” podcast with Beverly Clark which will soon appear here.

Also I have been busy with Edtech demonstrator work, delivering free training to schools via the United Learning Edtech Programme. If you need any help with Edtech: I can help as an official Edtech demonstrator, or with Computing: I can help as a CAS Master Teacher. Just reach out on Twitter @MrAHarrisonCS.


Core and Hinterland

This is a sneak preview of an article I wrote for Hello World magazine, whose “Big Book of Computing Pedagogy” is out now!

The Core and the Hinterland – why reading around the subject improves your teaching.

Having a laser-like focus on the exam board specification while teaching GCSE is extremely worthwhile: the exam is, after all, how they will be assessed. Knowing the difference between a worm and a virus will gain a mark. What won’t score on the exam is knowing that the first worm, called “Creeper”, dates back to 1971. Telling the examiner that the worm’s author Bob Thomas of BBN wrote the “Reaper” worm to get rid of “Creeper” is also pointless. But the teacher that knows this “hinterland” knowledge and can share it with their students brings colour and interest to the subject which can improve engagement. And teachers of Key Stage 3 and earlier should be delivering a rich curriculum that is enjoyable in its own right, while also laying the groundwork for GCSE studies. In short, there is great pedagogical value in exploring the hinterland with your students.


What are “core” and “hinterland”?

We can think of the core as the examinable material, what do they need to know to pass the exam? But as Christine Counsell warns in her 2018 blog: “if for the purposes of teaching, we reduce it to those propositions, we may make it harder to teach, and at worst, we kill it.” [1]

Counsell makes the point that students of English who commit to memory the plot, characters and stylistic features of a text from the revision guide will undoubtedly do well, but a true understanding can only be gained by “reading, bathing in the text, delighting in the text, alone and with others.”ibid

In his blog post “Signposting the hinterland…”, Tom Sherrington explains that the hinterland is as important as the core, and serves the purpose of:

  • increasing depth: niche details about a particular area of study that deepen and enrich the core.
  • increasing breath: wider surveys across the domain of any curriculum area that help to locate any specific core element within a wider frame. [2]

Sherrington give several examples including a music teacher sharing “a timeline of musical genres through samples from Purcell to Bjork – something we reference repeatedly as we explore our chosen composers in more depth”.

What is our hinterland?

Like the music teacher, we too can illuminate the subject with reference to the past. The backstory of computing is interwoven with world history and I regularly discuss new learning in the context of historical events. Teaching algorithms? Start with the origin of the word (Persian scholar Al-Khwarizmi of the Islamic Golden Age) and discuss how John von Neumann (yes, he of the architecture) devised Merge Sort to crunch numbers for the atomic bomb that fell on Nagasaki. Explaining validation? Tell the story of Margaret Hamilton’s Apollo computer “Lauren bug” and why it caused her to invent Software Engineering. [3]

We can find a computing “angle” in almost any event of recent history. From the encrypted messages sent during the Babington Plot against Elizabeth I to the problem of racial bias in algorithms used by 21st century police forces, bringing these narratives into class helps illuminate the topic, improve engagement and make learning stick around in long-term memory.


Why is hinterland important?

The new Ofsted inspection framework requires us to give learners the “cultural capital to succeed in life.”[4] The phrase “cultural capital” is often summarised as “the best which has been thought and said”, and as such it is the legacy left to us by the great minds of the past, and every child’s birthright. Computer science hinterland knowledge can also help learners build their cultural and science capital which is important if they are to see themselves as scientists or even computer scientists.[5]

Several of the pedagogy principles published by the NCCE[6] can be delivered through exploration of the hinterland, in particular the reference to storytelling in their advice to “make concrete” the learning (see box).

Bring abstract concepts to life with real world, contextual examples and a focus on interdependencies with other curriculum subjects. This can be achieved through the use of unplugged activities, proposing analogies, storytelling around concepts, and finding examples of the concepts in pupils’ lives.

NCCE 12 principles of computing pedagogy link

The hinterland paradox

Science and pedagogy blogger Adam Boxer makes clear the paradox of core and hinterland in his blog:

“there is content which we wish students to remember, and by contrast content we don’t deem necessary for them to remember. [But] without the ‘stuff we don’t need our students to remember,’ our curriculum becomes denuded of wider meaning and majesty: it ceases to be one thread of the epic story of humanity and becomes a sterile and sanitised exam-ready product.” [7]

It can be hard to solve this paradox, but teachers would do well to not shy away from the hinterland at all costs. I know that when I delve into the hinterland the learners are usually engaged and find it valuable. Indeed the “Von Neumann’s Merge Sort led to the Atom Bomb” story got a round of applause, that I am telling myself wasn’t entirely ironic!

The full article will appear in a future edition of Hello World magazine.

[1] ” Senior Curriculum Leadership 1: The indirect manifestation of knowledge: (A) curriculum as narrative” – Counsell, C. 2018.

[2] “Signposting the hinterland: practical ways to enrich your core curriculum.”, Sherrington, T. 2019

[3] “How to Teach Computer Science”, Harrison, A.J., 2021, John Catt Educational

[4] Education inspection framework (EIF), Ofsted 2019

[5] “Science Capital: making science relevant”, STEM learning blog 16 Jul 2019,

[6] Teach Computing quick reads,

[7] Core and hinterland: What’s what and why it matters, Boxer, Adam, 2019,


“Unplugged lesson?” Sure, just teach the knowledge without computers.

A previous blog post made it clear how I feel about the subject being called ICT. I even sent an email to all internal stakeholders this year making clear the distinction between Computing (National Curriculum title and the name of the KS3 subject), and Computer Science (the name of the qualifications we offer in KS4 and 5). We do not teach ICT.

ICT was characterised by practical skills: learning how to use software for purposes such as office productivity, communication, control systems and simulation. But Computing is a different beast: we teach the foundations, applications and implications of Computing. The KS3 section of the national curriculum document here contains a summary of the learning objectives in bullet points, each one beginning with a verb such as “understand”, “design”, “use” or “create”. without looking, have a guess what percentage of bullets begin “understand”. Answer after the ad…


The KS3 National Curriculum LOs include five bullets beginning “understand” and the other four are “use”, “design”, “undertake… projects” and “create, reuse and revise”. So five out of 9 or 55% of the LOs require acquisition of knowledge. There is no need to involve a computer in any of these, and much of the other objectives can also be taught without a computer.

Don’t get me wrong, I love using computers in my teaching, but I don’t feel I have to for much of the curriculum. So much is knowledge and understanding, that teaching it is just teaching. Techniques that work in the history classroom or the science classroom will work just as well in the computing classroom. It’s not ICT.

This blog was prompted by a request on Facebook for an “urgent unplugged lesson for Year 7”. My response was “teach whatever is on your curriculum for that day, just do it without computers.”. The national curriculum is more than 50% “understand”. Teach them to understand.


Kahoot goes into the cupboard of shame!

Has Kahoot had its day? Read on…

Keeping on top of the research and best practice ideas in Computing can feel like a struggle. This is actually a good thing, because it shows there are a lot of great people cracking on with driving our subject forward. But how to stay up to date and not drown? I like podcasts. One in particular has become a must-listen and I am catching up with old episodes this holiday.

Learning Dust: CAS Master Teacher Andy Colley and his sidekick IT Manager Dave Leonard have had a stellar lineup of guests on their pod since starting just over a year ago including Miles Berry, Prof Damian Hughes and Tom Sherrington.

There was controversy in a recent episode, when creator of and Director of Computer Science at Outwood Grange Trust, Tristan Kirkpatrick dared place “Kahoot” into the “Cupboard of Shame”. Why? Because it encourages speed of answers over depth of thought. Students race to be first, rather than right.


For what it’s worth I totally agree, which is why I use Forms, Quizziz and Quizlet, and occasionally Quizlet Live, instead of Kahoot now. What say you? And what podcasts do you listen to? Comment below, or on Twitter.