Balancing internal and external resources, and task demand

Reading time – 3 minutes

I’ve been using the model of cognitive load from Sweller of intrinsic, extraneous and germane load for a while now (Making practical work more effective; Improving practical work with integrated instructions). I’ve found it helpful to delineate what makes tasks hard for students (and teachers), and how they can be tackled.

For example, intrinsic load – getting the instructional flow right, extraneous load – use of integrated instructions.


Another useful model that I’ve been thinking about recently comes from Reif (Applying Cognitive Science to Education, 2008, MIT Press), that others have also written about. I like the use of the equation – it fits well with the centrality of proportion and ratios in a lot of what I teach.


However, I wanted a more visual way of trying to represent this. Pondering during a Year 8 lesson on moments the other day, I wondered whether the use of a see-saw might be useful.

Consider the two types of the resources a person has when problem solving – the external resources (written down keyword definitions, use of a peer or expert teacher, calculators, equation sheets etc) and internal resources (prior practice, knowledge of times tables, experience with standard equipment etc). The balance of these two will change over time as the student becomes more expert and therefore they will be able to tackle more demanding tasks – i.e. greater external resources needed early on, fading to higher reliance on internal resources later on.

How does this look as a model? A see-saw with a moving pivot. The position of the pivot represents the task demand. The resources sit either side, external to the left and internal to the right.

Early on, task demand is low, pivot lies to the left. To be able to tackle the problem, the cognitive load needs to be balanced, a balanced see-saw, hence large external resources are required, due to the low internal resources are available.


As the student progresses, tasks can be more complex as the internal resources are increasing, and fewer external resources are required.


As an expert in a task, relatively few external resources are required as the student has a large internal resource to call on.


If there are too many / inappropriate external resources then the student becomes overloaded trying to deal with these, and task completion is compromised –  the see-saw isn’t balanced.


If the external resources aren’t great enough, the student’s internal resources are insufficient and is overloaded by the task demand and task completion is compromised – the see-saw isn’t balanced.


I don’t think it is a perfect model – having the see-saw tilted towards internal resources may imply something it isn’t supposed to – i.e. you can balance the cognitive demand see-saw by making the task more complex. However, I think the idea that the cognitive load is imbalanced may be helpful – either the student is cognitive overloaded so can’t make efficient progress, or the task is just too easy so they aren’t making good progress (noting of course the benefit of over-practice in learning.)

I’m sure others have had these thoughts before, but its fun to write about interesting things, and it helps solidify my thinking. Any thoughts on this model?

Also, if you’d like a good read on Applying Cognitive Science to Education, Frederick Reif’s book is a good reference text. Certainly one I wish I’d come across earlier in my teaching career, and an erudite source derived from many decades of teaching.


Brain and teacher images from




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