Why Bar-Model Works #1: Dual Coding

I have been using bar-model incidentally in my year 11 revision groups for a couple of months now. I usually just sketch the bar while I’m explaining. This example was from a radioactivity question.

GM bar model (1)
Calculating the rate by subtracting background.

In the past I would have written this as an equation:

measurement = source + background

But the bar-model seems to cut through to the meaning faster. My students look at the bars and nod. And then they answer the question.

I have a couple of explanations for this. Today I want to write about dual-coding (the next blog will be about reducing extraneous cognitive load using bar-model).

Dual-coding is when we combine an image with verbal information. This has been shown to improve long-term recall. So in this example, as I describe how to calculate the source count, I am pointing to the bars instead of pointing to an equation.

When I used to point to the equation while I explained, I was combining words with words, overloading the working memory (see and hear LearningScientists here).

If you like bar-models, a group of science bar-model pioneers have begun to upload our blogs and tweets here.

In my next post I will explain how bar-models reduce cognitive load for learners.


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