The most depressing fact in all of education!

Take a look at the graph above. It shows something called “the forgetting curve” and it makes for depressing reading. What it means is that when you learn something new, within an hour you will have forgotten more than half of what you learned and within 24 hours you will only be able to remember about a third of what you knew the previous day.

Within a month you will have lost about 80% of what you learned.

This is not new research, in fact it was published in 1885 by a German Psychologist called Hermann Ebbinghaus who spent years learning three-letter ‘nonsense’ syllables and recording how much he could remember of them over different periods of time.

This was groundbreaking work: noted psychologist William James (“the founder of American psychology”) called the studies “heroic” and said that they were “the single most brilliant investigation in the history of psychology”.

Trying to hold water in a colander

In his book “Brain Rules”, John Medina said that Ebbinghaus discovered “the most depressing fact in all of education” and you can see why in the table below: people will forget most of what they learned in a class within a month, and the majority of this forgetting takes place in the first few hours after learning something.

It’s like trying to hold water in a colander:

ebbinghaus forgetting table

Forgetting is a good thing!

In all this doom and gloom, we should understand that forgetting is actually a perfectly right and correct thing for our brain to be doing.

We need to forget because we wouldn’t be able to function properly if we could remember everything: forgetting allows us to prioritise the important things and let go of what is irrelevant to us. We retain what we need and that has allowed us to survive and thrive as a species.

The trick is to explain to get our brain to understand that the stuff we’re reading is a priority for us and needs to be held onto.

All is not lost!

All is not lost, though, because Herr Ebbinghaus discovered that you can increase the lifespan of a memory by repeating your exposure to the information in timed intervals. The more repetition cycles a memory received, the more likely it was to persist in his mind. To begin with a memory trace is very fragile but, with repetition, memories strengthen and become stronger, ultimately reaching the point where they are permanent.

What this means is that if you have an hour, say, to spend on learning something, you will remember more, and remember it for longer, if instead of doing a one hour session today, you do 30 minutes now and 30 minutes on a different day, or spread out 20 minute sessions over three different days.

  • You’re not spending any more time.
  • You’re not working any harder.
  • But you remember more and you remember for longer.

In his book “How We Learn”, Benedict Carey said (referring to spacing out your learning), “The oldest learning technique in memory science is also one of the most powerful, reliable and easy to use.”

And to quote John Medina (“Brain Rules”) again, “repeated exposure to information at specifically timed intervals provides the most powerful way to fix memory into the brain”

Let’s walk through a cornfield, shall we?

A useful metaphor is that of a person walking through a cornfield: do it once and you may see a small trace of their footsteps for a while but it won’t take very long before the grass stems will flex back to where they were to begin with and there will be no trace of anyone having walked there.


Have that same person walk through the field repeatedly and you will end up with a visible track that will stay there long-term; re-visit that track at regular intervals and the track will be there permanently, rather like the stone age tracks that can still be found marked on the ground in the English countryside.

This is powerful stuff.

And according to an extensive review of the literature by Dunlosky et al, with I mentioned in my blog Put down that highlighter!, this ‘distributed practice’ was found to be the most effective learning method.

In a later blog I’m going to be talking about the best intervals to use if you have an exam a particular number of days, weeks or months away.

But in the meantime, get spaced out!



Photo credit: Mark Kent





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