Not many in the education world will have failed to have heard about Cognitive Load Theory (CLT). The theory was propelled into the limelight by a seminal tweet made by Dylan William last year and has since been the subject of much discussion among various educationalists.

I’m going to paraphrase the theory here, but my understanding of it is that there is only so much information that can be held in working memory at any time, but one way of short-cutting this constraint is to memorise important building blocks (or schemata) into long-term memory, which has infinitely more capacity. These schemata in our long-term memory can then be brought forward at any time to assist our working memory in thinking about more complex problems. On the other hand, if we ask our students to try to juggle too much new information at once, the result will be cognitive overload, or that blank, confused stare which means you have totally lost them. One way forward is to only teach new concepts in small increments and practise them extensively before moving on to the next new thing – in this way building up all those vital schemata in long-term memory.

I have read about CLT with interest and found the arguments persuasive, though I was a little doubtful about Dylan William’s assertion that it was the single most important thing for teachers to know. However, two experiences this week have forced me to re-evaluate my thinking on this.

The first experience was at home with my 9-year old son. He had some maths homework to do on Mathletics (an online app for children to practise maths) and I could hear him groan in frustration from across the room. Upon further investigation, it turned out that his Mathletics homework involved solving some long multiplications, and that he had absolutely no clue what to do. I prodded him a little by asking him what the steps are in solving a long multiplication. “I don’t know”, was the answer.

“Didn’t your teacher explain how to do it?”

“He did but I didn’t understand it.”

“What bit didn’t you understand?”

“I didn’t understand anything”.

His voice had now risen in frustration. He then produced a sheet of paper for me and said the teacher had handed it to the students who still were unsure about the process of solving long multiplications. He had been studying this sheet of paper, trying to understand, but looking at it made him even more confused.

I had a look at the sheet. For someone like me who understands the concept, the sheet made logical sense, but I was not surprised that a novice like my son would find it confusing. Firstly, there’s just so much to take in. Six boxes filled with text and numbers, and the confusing use of letters to denote numbers. A novice will look at this sheet and think, oh my goodness this is so complicated, and then give up.

So, we started from scratch all over again, and I was painfully aware that I had to make my explanation clear and simple or else risk losing him all over again and reinforcing the negative feelings he was developing about not being good at maths. I was particularly frustrated because we had been through something like this two years ago. Back then I had had to step in and tutor him because he had claimed he couldn’t do maths and was making remarks such as “I’m not clever”. We had spent 20 minutes a day for a few weeks or so during the Summer holidays, with me explaining concepts to him and getting him to practise them. His improvement was rapid, to the extent that when he started year 3 and had to fill out a card about himself, he wrote this.

By the way, I’m happy to report that he did indeed improve his writing and won a pen license!

I decided to get the mini-whiteboard out and model for him exactly how to do a long multiplication. I had to think of how to model this on the hoof, but I came up with using different whiteboard colours for each of the main steps.

The first step was to write out the multiplication in black. I made sure he knew how to lay it out on the grid. Then I switched to a blue pen and circled the number “8”, explaining we start by multiplying this with each of the numbers above. I made sure to repeat my instructions before moving on to the next bit and to speak slowly and clearly. I decided to just write out the numbers to carry forward on the side, and to cross them out as we went along. I felt that inserting them under the main numbers in the grid would just make the whole thing look too busy.

Having finished with the first line, I then switched to my brown pen and circled the number “6”. Now we multiply “6” by all the numbers above, but before we do this, we write a zero here. And I modelled the process for him, explaining in very precise, succinct terms what I was doing. Finally, the last step was done in green, where we basically added up each column.

I then wrote down another long multiplication for him to try out by himself. What pleased me was that he got all the steps right. He knew where to start, and where to proceed next. He didn’t get the multiplication right because he was let down by his poor times table knowledge. I thought he had these in the bag, but it seems not all the information was firmly embedded in long term memory. We practised a couple more long multiplications, and he progressively got more confident. He knew just what to do and was no longer confused. He had a clearly mapped out plan of action.

But of course, it was clear to me he needed to master his times tables. I tested him on a few of the tables and had some interesting results. For instance, he paused a long time before giving me the answer to 6×4. He then admitted that he knew 2 sixes made twelve, and that he had been adding up twelve and twelve in his head. Can’t fault his logic there, but such calculations take up too much working memory. His answer needs to be automatic, practically without thinking.

This is something we are going to have to remedy. Why oh why, though, is it me having to do this and not his teacher at school? I remember regular drills of my times tables at school when I was young. I don’t think my mother ever had to step in to ensure I learned them. If we think of this times table knowledge as one of the vital schemata required in long term memory before children can successfully attempt long multiplication and long division, then it’s a mystery to me as to why that knowledge is not checked, just like a phonics check, though perhaps more informally (i.e. not state mandated).

As we put the whiteboard away, I asked my son if my explanation of how to solve long multiplications had been more understandable than the teacher’s. And then the truth came out. “I don’t know. I was distracted by the displays on the wall. I like looking at the enrichment tasks, you know, the pieces of work other children have done. I also like looking at the clock and adding different times to see when it will be lunch time.” So, whatever technique the teacher used to explain how to do long multiplication was lost on my son because he was distracted by the displays on the wall and by the clock.

Another nugget of information then came my way. “The teacher goes really fast, like he’s in a big hurry and he doesn’t give me time to think.” A fast-paced lesson full of energy might work fine for some, but it can mean others are left behind, particularly if they have not yet mastered the concepts being learned. When being subjected to a quick-fire barrage of information, some children can suffer from cognitive overload and shut down altogether. I’m guessing something like this must have happened with my son. For he is perfectly capable of learning how to do long multiplication. A systematic approach that took into account Cognitive Load Theory would have helped him, and many others like him, not to fall by the wayside needlessly. In retrospect, there are several key areas where a CLT approach might have ensured a different outcome:

- An understanding that knowing times tables is a vital schema that needs to be embedded in long-term memory as a precursor to moving on to doing more complex calculations such as long multiplications. This should have been checked and remedied.
- An awareness that busy displays on walls can be distracting, using up critical working memory when the pupil should be focusing on the teacher explanation. Wall clocks should also be positioned out of pupils’ sightlines.
- When teaching a complex process that involves several steps, to think about how to display that information in a way that reduces cognitive load. On reflection, my modelling of the long multiplication using a different colour for each step was a way to simplify the tasks in a visually appealing way. This is, if I understand it correctly, a lot of what dual coding is about. Whereas that busy yellow sheet was the opposite of dual coding. It invited pupils to try to process too much information at once and had little to help them short-circuit working memory constraints.
- There was also an issue with the fast-paced barrage of information being delivered in one go. While it might be tempting for teachers to up the pace and inject some energy into proceedings, it is important to remember that new concepts must be taught slowly and in small increments, to allow working memory to cope.

*I have spent so much time on this one experience that I have not got the space in this blog to talk about the other thing that has made me re-evaluate the importance of Cognitive Load Theory. This was the implementation of the Sounds-Write phonics programme in my Reception class. I will have to write about this in a future blog. For now, I hope I’ve made a strong case for the importance of CLT for teachers.*