Dual coding in the classroom: when is it effective?

You likely already use dual coding in your teaching, whether you realise it or not.

The practice simply involves combining words and pictures to help pupils learn; for example, reading a story book with pictures, or showing a diagram to your pupils while explaining a new concept.

However, the evidence for dual coding is mixed. In a previous review of cognitive science in the classroom, the Education Endowment Foundation (EEF) found that while dual coding can help pupils to learn, on occasion it doesn’t.

In a new piece of research, we expanded on the EEF review to find out why this is, and found that how visuals are designed and used is key to making dual coding effective.

The science behind dual coding

The theory behind dual coding is that our long-term memory is formed through both language (words and phrases) and images (what we see around us), so when pupils learn from a combination of these sources, they can form stronger memories.

For example, if pupils read about the Romans and also see pictures of them, they should remember the facts better. For this reason, dual coding especially helps pupils to learn and retain new knowledge.

However, learning is often more complex than this. To benefit from dual coding, pupils need to attend to both sources - visual and linguistic - and integrate these into one mental model, while working within the limits of their working memory and attention.

When does dual coding work best?

We analysed 56 studies where dual coding was used as part of classroom teaching. The studies evaluated a range of visuals across primary and secondary settings, from whole-class teaching to small-group or one-to-one interventions. We learned several important things in our study.

Firstly, dual coding can benefit all pupils’ learning, but it is more effective for secondary-age students than for primary. This doesn’t mean that visuals aren’t helpful for younger pupils, as they may have other benefits such as engaging them in reading or providing discussion points.

Secondly, dual coding is especially helpful when the pace of the lesson is set by the teacher or constrained by a time limit, rather than when pupils pace themselves; for example, when a teacher explains an idea to the class. In this context, visuals provide a useful tool to support pupils’ working memory and cognitive load.

Thirdly, dual coding is often used as part of targeted support for pupils with special educational needs and disabilities, but we found limited research on how effective it is for these pupils. However, dual coding was more effective during whole-class teaching than for smaller-group or one-to-one interventions. This suggests dual coding is effective as part of the universal offer for all pupils, rather than just as targeted support for some.

Most of all, while different kinds of visuals can help pupils to learn a range of subjects and types of knowledge, the way lessons and teaching resources are designed has a big impact on how effective dual coding is. Following three simple design tips can really help pupils to benefit:

Signal

Signalling the connection between visuals and words helps pupils to attend to and integrate the two sources of information. This might mean simply pointing to and talking about the pictures in a story, or annotating a diagram with key words. For instance, labelling a picture timeline of Roman history with key terminology from a knowledge organiser.

Segment

When using dual coding, segmenting content in a meaningful way really helps pupils to understand what they are learning without straining their cognitive load. For example, teaching the process of photosynthesis using a picture and explanation to clearly explain each step.

Simplify

Avoiding irrelevant information helps pupils to focus on what’s important without straining their cognitive load. For example, avoid using decorative pictures or icons in a PowerPoint presentation that have no relevance to the text on the slide.

Our findings also challenge a common assumption: giving pupils an extra task to do with the visual, such as copying or tracing it, did not bring any additional benefit to pupils’ learning. It won’t be harmful to do this, but given the preparation involved in creating accompanying activities, teachers may be better off focusing their time on getting the visual itself right.

Dual coding can be an effective support for pupils’ learning, particularly for secondary students and teacher-paced activities, but how it is used matters just as much as whether it is used.

The strongest message from the evidence is to be purposeful: use visuals to support the learning you want to achieve, and spend your preparation time making them clear, focused and easy for pupils to connect with the words around them.

Briony Banks is senior research scientist at Ambition Institute