Making the Juice Worth the Squeeze: Dual Coding

A teacher’s time is education’s most vital resource. In this series of blogs I explore some of the common aspects of classroom practice, give my opinion and what works and suggest some reasons why other things might not be worth our time. The aim is to share what I think are the most time efficient ways of getting the biggest pay off from a strategy.

Today I want to discuss dual coding. In my training sessions I am a big fan of ensuring that no one leaves without having some of their burning questions answered or discussed. So I like to start my sessions by having people write questions they hope to get answers to by the end of the session. This forms a secondary agenda and, while most will probably be covered in the session, some can be added and signposted along the way. 

The most common question I get in my teaching and learning sessions is about dual coding. People want to check they know what it is and why it is important. They then often bring up examples and ask ‘is this good dual coding?”.

I am going to go into a tiny bit of the theory of dual coding, but mainly I want to discuss the way it is interpreted and some of the common issues I think arise. Obviously you are free to disagree, it’s just my opinion and the reasons why.

Before I get started I do want to say that there are two resources that have been fundamental to my own understanding of dual coding. I would strongly recommend reading Pritesh Raichura’s blog series “Clear teacher explanations” a great Boxer blog and this blog on dual coding. If you are a more visual learner (LOL) here is a great talk from reseachED home.

Recently there was a thread on twitter that also discussed some of the issues with dual coding that often come up.

What is dual coding?

The Noun Project offer thousands of icons

As the learning scientists put it:

Dual coding is combining words and visuals such as pictures, diagrams, graphic organizers, and so on. The idea is to provide two different representations of the information, both visual and verbal, to help students understand the information better. Adding visuals to a verbal description can make the presented ideas more concrete, and provides two ways of understanding the presented ideas. Dual coding is about more than just adding pictures. Instead, the visuals should be meaningful, and students should have enough time to integrate the two representations (otherwise, cognitive overload could occur). There is scientific evidence backing dual coding, showing that when we combine representations it is easier for students to learn and understand the material.”

This makes dual coding quite a broad concept, and this is where the trouble lies. It becomes too nebulus a word to provide

What things are effective dual coding then?

Here is a non-exhaustive list of common teaching practices that are dual coding:

  • Talking about any image, graph or diagram
  • Drawing a diagram as you explain a process
  • Any kind of flow diagram or decision tree
  • The sparse use of words with symbols like arrows to infer relatedness, eg increase and decrease
  • Using icons which have explanatory power. These are icons that aid the explanation of a concept and provide a visual link between a concept and its concept. So in biology we often discuss the idea of a large surface area and an icon showing a simplified version of the folded membrane of the intestines might be helpful and aid the understanding.

What things are probably not effective dual coding then?

Some of the things often thought of as effective dual coding but probably aren’t. The use of images that lack explanatory power. These illustrations are commonly chosen due to the designers desire for a certain aesthetic. That’s fair enough as design is important in its own right, but it is not effective dual coding. There is even a risk that it creates confusion for the students and possibly distraction. As they try to link the image to the information they play a visual version of ‘guess what’s in my head’. This trend is not helped by PowerPoints love of offering design advice that populates these icons automatically.

Another poor use of dual coding I have seen is when an icon is used as a retrieval tool. The activity requires the student to recall details, say of a scene in Macbeth and the icons are on their sheet to act as a scaffold. This is well intentioned but runs the risk of turning the icon into a retrieval cue. This helps the student in the short term but as the icons are not readily available in the assessment they offer false promise. If the icons were instead turned into a simple diagram the students could draw then this problem is side stepped. 

At the end of the day it is easy to decide if something is effective dual coding or not. Just ask yourself “Have I chosen this image because it adds value to my explanation or because I like the way it looks?” It is also worth trying to view your resources through the eyes of your students. Will they be able to make the links you make when they see it or will it be too complex?

The whole point of this blog series is to help teachers who are exploring these ideas for the first time to understand them in sufficient detail so they can forgive themself if their design skills are not on par with the most aesthetic examples. I’m not the only one who has had this issue. Fortunately my concern is backed up by Daniel Mujis, former head of research at Ofsted. He shared this research paper that discusses the positive and negative effect of including relevant and irrelevant images. 

The vagueness of the term dual coding has recently been combated by the introduction of a number of other terms to try and codify certain techniques that fall within the umbrella of dual coding. ‘Word diagrams’, ‘Advanced organisers’ and ‘Graphic organisers’ are all terms that have been used for various aspects of dual coding. I welcome any language that helps teachers debate how this idea from cognitive science can be effectively used in the classroom. At the end of the day, granular actionable techniques are what teachers need to ensure that can make the best choices for their students and have a healthy debate on what works and what doesn’t.

PS In this blog I have deliberately ignored the use of dual coding in resources for teacher CPD. This is none of my concern as teachers have a certain amount of expertise, experience and literacy. I’m really only focused on how novices interact with resources in this blog.

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