The Greatest Breakthrough in the Science of Education Over the Last Century

If you understand the interplay between working memory and long-term memory, then then you can actually derive – from first principles – the methods of effective teaching.

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What’s the greatest breakthrough in the science of education over the last century?

Characterizing the mechanics of learning in the brain. Learning is all about the interplay between working memory (WM) and long-term memory (LTM).

If you understand that, then you can actually derive – from first principles – the methods of effective teaching.

How Information Gets Transferred Into to Long-Term Memory

The goal of instruction is to increase the quantity, depth, retrievability, and generalizability of concepts and skills in a student’s long-term memory (LTM).

At a physical level, that amounts to creating strategic connections between neurons so that the brain can more easily, quickly, accurately, and reliably activate more intricate patterns of neurons. This process is known as consolidation.

Now, here’s the catch: before information can be consolidated into LTM, it has to pass through working memory (WM), which has severely limited capacity.

The brain’s working memory capacity (WMC) represents the amount of effort that it can devote to activating neural patterns and persistently maintaining their simultaneous activation, a process known as rehearsal.

Most people can only hold about 4 chunks of coherently grouped items simultaneously in WM, and only for about 20 seconds. And that assumes they aren’t needing to perform any mental manipulation of those items – if they do, then fewer items can be held due to competition for limited processing resources.

Limited capacity makes WMC a bottleneck in the transfer of information into LTM.

How to Teach to Avoid Overloading Working Memory

When the cognitive load of a learning task exceeds a student’s WMC, the student experiences cognitive overload and is not able to complete the task.

Even if a student does not experience full overload, a heavy load will decrease their performance and slow down their learning in a way that is NOT a desirable difficulty.

Additionally, different students have different WMC, and those with higher WMC are typically going to find it easier to “see the forest for the trees” by learning underlying rules as opposed to memorizing example-specific details.

(This is unsurprising given that understanding large-scale patterns requires balancing many concepts simultaneously in WM.)

It’s expected that higher-WMC students will more quickly improve their performance on a learning task over the course of exposure, instruction, and practice on the task.

However, once a student learns a task to a sufficient level of performance, the impact of WMC on task performance is diminished because the information processing that’s required to perform the task has been transferred into long-term memory, where it can be recalled by WM without increasing the actual load placed on WM.

So, for each concept or skill you want to teach:

• it needs to be introduced after the prerequisites have been learned (so that the prerequisite knowledge can be pulled from long-term memory without taxing WM)
• it needs to be broken down into bite-sized pieces small enough that no piece overloads any student's WM
• each student needs to be given enough practice to achieve mastery on each piece -- and that amount of practice may vary depending on the particular student and the particular learning task.

Dealing with Forgetting

But also, even if you do all the above perfectly, you still have to deal with forgetting. The representations in LTM gradually, over time, decay and become harder to retrieve if they are not used, resulting in forgetting.

The solution to forgetting is review – and not just passively re-ingesting information, but actively retrieving it, unassisted, from LTM.

Each time you successfully actively retrieve fuzzy information from LTM, you physically refresh and deepen the corresponding neural representation in your brain.

But that doesn’t happen if you just passively re-ingest the information through your senses instead of actively retrieving it from LTM.

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