What are the Cognitive Loads of reading and how can we reduce them?

Reading is a physics problem that doesn’t receive much attention in class. I think it should. Science professionals read a lot:


How many hours of professional STEM reading per week?


It turns out that the people who responded to the survey read a lot. Almost 85% of them read professional texts for more than 5 hours per week and 20% of them read for more than 15 hours per week. And they read to learn…


Why STEM professionals read

But most weren’t taught to do it at school. 


Who teaches scientists and engineers to read professional texts?

This last chart troubles me. I know STEM texts (exams, textbooks, papers) are different to other texts. They use different vocabulary; follow different conventions and have a different purpose. Either learning to read these texts is so easy, it doesn’t require teaching, or it is hard and we are letting learners down.

How many capable young scientists and engineers are dropping out because they can’t access the information in texts? I worry about this a lot.

Cognitive Load Theory explains why reading is difficult and tells us how to make it easier. All three memories are in use:

  • long-term memory – the knowledge you already have. Commit as much to memory as possible – use quizzes every lesson. 
  • working memory – where we compare what we’ve read to what we know and try to make meaning. There isn’t much we can do to boost this, though a good night’s sleep always helps me. 
  • external memory – the text, and any scribbles you’ve added to it. This is a skill and we should teach it. 

Comprehension depends most on what you already know. The two most important things for reading are in your long term memory (or they need to be). They are vocabulary and knowledge. Readers who are equipped with these are equipped to understand texts.


Science teachers are good at teaching science vocabulary. We explain clearly; we use example sentences; we revisit; we match words to diagrams. We use every trick we know.

But we ignore key non-specialist vocabulary. Words like: determine, suggest, establish and  system (I took these from a couple of recent GCSE papers).

These words should be taken as seriously as technical vocabulary. It is hard to choose words to focus on. I tend to teach words as I come across them in textbooks and exam papers (especially if I think they could come up again).


Along with vocabulary, the most important part of understanding is what you already know: your schemata. As we read, the information in the text is held in your working memory to be presented to knowledge from your long-term memory like a debutante or a novice speed-dater. If sense can be made, great. If not, the reader has work to do. 


Skills get tough press – but there are a few reading skills (or habits) which make a difference. These are the four that expert science readers (like us) use most often.


  • I Wonder…. Expert readers ask questions of the text. Often these questions are related to meaning, but they can be “I wonder what that word means?” or, “I wonder why the writer said that…”
  • In other words…. Paraphrasing (rewording, often making clearer) is a powerful comprehension checking skill/habit.
  • I predict…. Asking readers to predict what comes next in a test is a useful way of drawing attention to the structure and conventions of scientific texts – it is extremely useful when scanning a text for the information you want to be able to predict whether the information might be in a nearby section.
  • So far… Summarising is a habit which encourages prioritisation of information.


If these activities can be practiced enough (several times over a few weeks, with occasional top-ups) they quickly become part of a reader’s reading schema, increasing your students’ ability to learn from texts.

This blog is a development of the blog I wrote in 2015 for the Royal Society of Chemistry – here. I am reassured to find that I still agree with most of what I wrote then. Thank you if you’ve stuck with me all this time!


Integrating Questions and Diagrams to Reduce Cognitive Load for Novice Physicists

I think this will be the last of my problem-solving blogs for a while – it’s a little one about reducing the split-attention-effect.

In this series of blogs, I have suggested strategies to reduce the cognitive load of problems, so that novices can focus attention on the elements you want. This one is about text and diagrams.


From AQA 2016

Continue reading

Using Worked Examples to Reduce Cognitive Load in Physics

Screenshot from 2017-04-29 11-12-05

from Cognitive Load Theory – Sweller, Ayrea, Kalyuga 2011 (art by @@olivercavigliol – https://teachinghow2s.com/docs/CLT_chapter_summaries.pdf)

Learning how to solve problems is the key to becoming a physicist (here and here). The problem with problem solving is that you need to be pretty knowledgeable before you can make a good go at it. And we tend to teach new information and then put it into a problem in the same lesson. This doesn’t work for most learners.

The science of learning – cognitive load theory – has found the best way to to teach problem solving: worked examples.  Hattie puts the effect size of worked examples at 0.57 – 7 months extra progress per year.

Screenshot 2017-04-29 at 13.40.24

from Story of a Research Program by John Sweller

When a teacher models how to solve a problem, she is giving the guidance that novice physicists need. She will make the hidden process of solving the problem visible. It is a way in.

But then what? The jump from seeing someone do it to being able to do it yourself is still big.: “novice learners reach apoint of working memory overloadvery quickly” Hattie, Yates. 2014). Learners need a bridge.

One method is to give learners partially completed problems – this method is called problem completion. This reduces the cognitive load, allowing the learner to focus his working memory on fewer aspects of the problem.

Here is an example:

Worked Example

Terminal Velocity Q AQA 2016

AQA June 2016

Teacher’s explanation

Imagine you are standing at the board – ideally the question is projected adjacent to where you are explaining and making notes for the class:

  1. The weight of the ball is independent of the ball’s speed – it doesn’t change.
  2. The drag on the ball increases as the ball accelerates.
  3. The ball stops accelerating when the drag matches the weight – it has reached terminal velocity.

Completion Problems…

Going straight from worked example to whole questions is very challenging for most learners. Sentence starters reduce the cognitive load:

On 14 October 2012, Felix Baumgartner created a new world record when he jumped from a stationary balloon at a height of 39km. Above the Earth’s surface. 42s after jumping, her reached a terminal velocity of 373 m/s. Explain in terms of weight and drag how terminal velocity is reached.


  1. The weight ________________________________________________________________________
  2. The drag __________________________________________________________________________
  3. When the drag has increased _____________________________________________________

One completion problem will not be enough. You will need lots. There are plenty available in past papers, however, there is a cognitive advantage in including individuals in the class:

When his balloon experiment began to go wrong, Mr Rogers knew he had to jump. He was 5km high. Explain in terms of weight and drag why he reached terminal velocity as he fell.


  1. The weight ______________________________________________________________________
  2. The drag ________________________________________________________________________
  3. When the drag has increased ____________________________________________________.

Other insights from cognitative psychology include spacing out the practice and interleaving. I suggest revisiting these problems regularly and mixing them up with other questions. Aim for success – there are benefits for students getting it right. Optimum challenge is great, but getting answers wrong makes it more challening next time.

In my next blog, I will describe another strategy for reducing the cognitive load for novice physicists – cooperative learning.
I found @olivercavigiol teachinghow2s.com helpful in writing this blog.