Education researchers usually now talk of increasing interval retrieval practice whereas spaced repetition system, which is favoured by computer programmers.
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He called the graph below the die Vergessenskurve1 or in English the forgetting curve.
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We know active review works better than just reading though. How lucky that answering a maths problem is actively reviewing, providing we are not reviewing exactly the problem we have done before. Merely repeating the same problem allows learners to take a short cut by just remembering the answer.
We know that making links within our brain, which is perhaps the same thing as learning things we understand, works better than trying to learn seemingly arbitrary nuggets of wisdom.
We know that there are other factors, which are harder to pin down involved in how fast our memory decays.
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Video on how the spaced repetition system works
This is the same video increaseLTMduration.mp4 found on the first page of Explaining and Training increaseLTMduration.mp4 page - you might want to watch only the first 3 minutes.
Forgetting in low attaining classes.
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