Not remembering
everything you need to?
Learn how to beat the
forgetting curve.
October 2022 | The Learning and Wellbeing Team

Every student’s been there. You had it memorized the night before, and you were ready for the test. But now you can’t seem to remember what you thought you knew last night. You are starting to forget. Not only are you starting to forget, but you know you are forgetting, and the panic is starting to set in. Worry, anxiety and stress can explain some of that difficulty recalling what you thought you knew. But the main reason you are forgetting is best explained by the forgetting curve

In the late 1880s, a German psychologist discovered the forgetting curve, which describes the rate at which information is forgotten. This curve, depicted in the figure below, shows that after just 20 minutes up to 42% of information can be forgotten and that after just one day only 33% of the information you were learning will remain. After two days, more than 70% will be gone. 

The forgetting curve explains how you can know something the night before the test and than not be able to recall that information on the day of the test. It also explains why cramming for the test the night before is not the best strategy. Our brains are designed to forget things, which can be very annoying but at the same time, probably a good thing. Imagine if we remembered everything that we saw, read or experienced every single day. Our heads would be filled with all of the unimportant stuff, along with the really important information.  This basic principle of learning, discover more than a hundred years ago, is still true and has been demonstrated (again) in more recent experiments on learning and recall 

Fortunately, Ebbinghaus, the German psychologist who discovered the forgetting curve, also discovered how to beat the forgetting curve.  He showed that simply rehearsing and repeating the information, spread out over a number of days and weeks would decrease the rate at which the information would be lost.  The figure below shows that with one rehearsal what you remember is recovered. But after one, rehearsal, doesn’t get forgotten as much — in fact after one rehearsal, 70% is retained and only 30% forgotten. With three rehearsals the amount of forgetting starts to become minimal. However, it is important to notice that the amount of time between rehearsal needs to be spread out. 

This strategy of repeatedly practising over a number of days is called spaced repetition.  If you have ever made and used a stack of flashcards and run through them over and over again, then you have taken the first step to beating the forgetting curve. Research has shown that practice testing (i.e., doing flashcards or practice problems over a number of days) is among the most effective and efficient learning strategies

How this all works: 

The key ingredient to beating the forgetting curve is active recall. Every time you force yourself to actively recall what you are trying to learn, you are strengthening your memory for what you are trying to learn. There are lots of ways to actively recall what you are learning. Flashcards is one way. You can tell someone, like your roommates, your friend, or your mom everything you know. You could have someone quiz you. All of these are examples of active recall, which is the key to retaining what you need to know. 

What makes flashcards one of the best ways is that allow you to go through a lot of material in a very systematic way and that they can be done anywhere. Flashcards are portable. They can be done on the bus, between classes. They can even be given to a friend or your mom to test you. 

There are a number of phone apps, like Quizlet, which work the same way as pencil and paper flashcards.  One advantage of Quizlet is that you can’t peak at the answer before answering a question. One disadvantage is that you may be able to find a set of Quizlet questions for your course that someone has already made and posted online. This is a time saver but you don’t really know if the Quizlet questions that you found online cover all of the material or are even correct. Better to make your own. 

What about practice problems in math or stats?

There are a lot of courses that will be based more on solving problems than remember facts, names, events or concepts. Doing practice problems repeatedly work just like flash cards. They force you to actively recall how to solve a problem, whether the problem is in math, physics, economics or statistic. 

Again, the key idea is to force yourself to do the problem over and over, until you can do even the same problem, quickly and from memory. Understanding how to solve a problem is not the same as being able to solve it, when asked, in a short amount of time — like on a test or exam. 

How to get started and tips to keep in mind: 

1. Make a lot of cards. You should make one flash card for every term, concept, idea, important event or person, or significant date. If you are not sure what you should be memorizing, ask the teacher, instructor, teaching assistant or professor. 
2. Make a lot of card. Just one term per flashcard.
3. Sometimes a drawing is more efficient. Consider putting a picture (e.g., of a cell) on the back of one card. Something drawing a picture of what you need to know if more efficient.
4. Making flashcards are a real pain. Remind yourself that it is still the most efficient strategy we know of. 
5. Don’t remove cards you know well. Even if you are getting card corrects, leave them in the stack. The forgetting curve says that as soon as stop rehearsing you will start to forget. You may decide to focus on a subset of cards that are giving you some difficulty, but make sure you do the entire stack repeatedly.  
6. Don’t peek at the answer. Say aloud or write down your answer.
7. Start early.
You should have all of your cards made and ready to rehearse 1 week before the test. You can also review cards as you make them.  
8. Follow the 3+3 rule. If you can recall your stack of cards three times in a row, over three different days, you have truly beaten the forgetting curve. 

Dunlosky, J., Rawson, K. A., Marsh, E. J., Nathan, M. J., & Willingham, D. T. (2013). Improving Students’ Learning With Effective Learning Techniques: Promising Directions From Cognitive and Educational Psychology. Psychological Science in the Public Interest, 14(1), 4–58. 
Ebbinghaus, Hermann (1913). Memory: A Contribution to Experimental Psychology. Translated by Ruger, Henry; Bussenius, Clara. New York city, Teachers college, Columbia university.
Murre, Jaap M. J.; Dros, Joeri (2015). “Replication and Analysis of Ebbinghaus’ Forgetting Curve”. PLOS ONE. 10 (7): e0120644. Bibcode:2015PLoSO..1020644M.

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