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!



Haven’t We Got Enough To Do Already? Why Science Teachers Should Teach Vocabulary and How to Make it Stick


There are words in the English language that science teachers wish the English department would teach – words like process, appropriate and monitor. We don’t expect anyone else to teach scientific vocabulary such as photosynthesis and nucleus, but if someone (English teachers?) could teach all of the rest, that would be great.

bitesize sankey
Tier 2 words: summarise, process, involved, x rather than y. http://www.bbc.co.uk/schools/gcsebitesize/science/aqa_pre_2011/energy/heatrev5.shtml

Worse luck – it doesn’t work that way. If you want your students to be able to read science textbooks and understand exam questions, teaching this sophisticated, but non-specialist vocabulary is down to you.

Specialists call these words tier 2. Here is my strategy for teaching tier 2 words in science. Continue reading “Haven’t We Got Enough To Do Already? Why Science Teachers Should Teach Vocabulary and How to Make it Stick”

Science: A Great Source of Metaphor…

Have you got time to read two very short science texts? Both of them are surprising and wonderful.

First text: a beautiful piece of writing by Lewis Thomas called ‘The Lives of A Cell’ (thelivesofacell)   – you will thank me for this.

Second text: the original paper by Crick and Watson (watsoncrick) announcing the structure of DNA (it’s 1 side of A4 and it is readable – just read it).

Crick and Watson – DNA model

Continue reading “Science: A Great Source of Metaphor…”

Imaginary Ice Block Discovered in School Field Causes Writing and Reading

Giant Ice Block Found in School

The whole of this blog centres on a mean trick (and I feel bad about it), which has produced something special, like pearl accreting around grit. I’m the grit.

Last week my colleagues and I pretended that a giant ice block fell into the school field. We dug a hole, put police tape around it and faked a letter from the local police. We intended it as a stimulus for reading and writing, which it has been, very successfully. We told the children that one of us believed it was an enormous hailstone, while I countered that it was obviously an ice meteorite. We were in role. They believed us. We were very convincing. We took it too far. They still believe it.

So, ignore the dubious heart of this tale. The work is worth it.

Continue reading “Imaginary Ice Block Discovered in School Field Causes Writing and Reading”

Guericke’s Sulphur Sphere

It seems reasonable to suppose that if the Earth has a fitting and appropriate attractive potency it will also have a potency of repelling things that might be dangerous or disagreeable to it.

Otto von Guericke 1663

Otto von Guericke was an extraordinary engineer. He is famous for inventing the vacuum pump (and disproving ‘nature abhors a vacuum’ – a pernicious error of the ancient Greek philosophers – Aristotle this time).

In 1654, Guericke used his pump to evacuate the air from his famous Magdeburg Hemispheres. These are two hollow hemispheres placed together and the air inside them pumped out. 16 horses were unable to pull the hemispheres apart – the most dramatic and famous physics demonstration of all time.  Continue reading “Guericke’s Sulphur Sphere”

The Versorium Needle

A draft extract from my book using narrative to teach the big ideas of physics:

These are the utterly false and disgraceful tales of the writers.

William Gilbert, 1600

I will start my history of electricity with an utterly false and disgraceful lie: amber, when rubbed, will not attract dried basil.

The ancient Greek philosophers had a method for finding the truth. Observation played a part, but only observation of naturally occurring phenomena. Experiments did not count, because experiments are artificial. Observation combined with reason was the preferred method of finding the truth. This produced excellent mathematics but dodgy science. They claimed that amber would not attract dried basil, but did not test this claim. Continue reading “The Versorium Needle”

Silent Reading: What’s Going On Inside?

bigoceanlinerThe student is silent. Eyes flick across the page. The page turns. It’s a good book. What could go wrong?

Silent reading is a good thing, but it isn’t teaching. It might be learning, but you don’t know that.

In class, reading is important, but you need to see the workings. You could assess at the end, but that’s too late. The best way is to get readers reading aloud and talking about what they have read.  Continue reading “Silent Reading: What’s Going On Inside?”

Science Teachers Are From Mars, English Teachers Are From Earth Usually.

I’m excited to have the latest ASE School Science Report (SSR) on Science, Literacy and Learning open in front of me on the train. I’ve got time to read it and write a short blog.

One article describes research on how English teachers and science teachers read a science news story differently (McClune and Alexander, Learning to Read with a Critical Eye: Cultivating discerning Readers of Media Reports with a Science Component, SSR Dec 2015).

Continue reading “Science Teachers Are From Mars, English Teachers Are From Earth Usually.”

An Accretion of Science Writers

Thirty science writers and teachers who write have formed a group to support and promote brilliant science writing for children and young adults.

Science writing for young people should inspire as well as teach; it must be map and guide. Young people need to be free to explore the universe through words. The writing must be very good.

This takes technical expertise; literary skill and an understanding of children’s learning. Our science writers’ circle brings writers together to share these skills to write outstanding science texts.

We meet online with a forum for sharing, discussion and feedback. We are a community with a common goal: brilliant science writing for young people.

The group is called the science writers’ circle and we are one week old. Watch this space.


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