The Forgetting Curve

To forget is human.  In many ways, the brain was designed to forget, thus allowing us to continue to function in this world brimming with incessant flows of new information.  But some things we want to remember, even if they don’t automatically stick in our long term memory banks.  At times, specific memory strategies are appropriate to help us overcome our forgetting instinct.

What can we do to help our students remember the rules, the strategies, and the content that will serve them on standardized tests and help them achieve success in the domain of high school academics? For some students, a single exposure to a new concept will be enough to firmly implant it into their memory banks. For example, if you teach these students how to “pick numbers” for an algebra problem, they will employ that strategy every time they are exposed to algebra problems in the future. Other students need multiple exposures to new material before they begin to integrate and apply it. At a superficial level, these students may “know” what to do, and if you cue their memory, they may be able to retrieve the concept; but on their own, without your input or retrieval cues, they will not independently use the concept.

All students, and all humans for that matter, have idiosyncratic memories.  Certain individuals have a “bear-trap” memory for pictures or images, but a weaker memory for numbers or names. Others have a gift for figures, data, or statistics, but struggle to recall sequential information, narratives or story lines. Everyone has a unique level of ability for recalling certain content, based on how one’s brain is designed, ones’ interest level, and the importance assigned to remembering particular content. If a student is lacking the will to learn the material, a tutor can address that through motivational channels, but if a student is trying in earnest to learn the content and is not succeeding, other strategies exist to help the student improve retention and study “smarter” rather than harder.

There are two specific strategies I want to offer that you can use to help students who are struggling with retaining concepts covered in your sessions.

More meaningful encoding

Before we discuss the first strategy, we must distinguish the two primary systems involved in remembering: Encoding (putting information into your memory) and Retrieval (recalling information from your memory).

The first strategy involves encoding material in a more meaningful way for the student. Basic exposure to content does not always make a strong enough memory trace to move the information from short term (working) memory into long-term memory storage. Some students need to find a way to make the material more personally meaningful for it to stick in long-term memory.  Here are some strategies that tutors can use to assist in this process:

  • Put the student in the teaching role. Allow the student to make her own meaning of the material and communicate the material back to you, in her language, using her examples. This “translation” can facilitate encoding into long-term memory.
  • As a tutor, you can create rules of thumb, heuristics, personally tailored for your students, in their language.  Short, simple rules of thumb, oft repeated and reinforced, have an easier time sticking in long-term memory.
  • You can create acronyms to help students memorize concepts.
  • You can create behavioral scripts tailored for your students: “When you see this particular word- I need a buzzer to go off in your brain. The instant you see this word- you must employ this corresponding strategy.”
  • You can use visual imagery to reinforce rules: “Every time you see a right triangle, I want you to mentally overlay the Pythagorean theorem on top of the triangle.”

There are many ways to make the memory “stickier” for the student and more likely to transfer into long-term memory.

Timely (same-day) repetition and retrieval practice

The majority of students, when they walk out of their tutoring sessions, will naturally put thoughts of the SAT or ACT out of their minds. They pick up their cell phones, they get back in their cars, they text their friends, and whoosh- thoughts of the SAT or ACT are gone. Some students will avoid thoughts of the SAT or ACT until the morning or afternoon of their next session.   They will save all of their homework and vocabulary review until the hours leading up to their next session. Though this approach works for certain students, it greatly disadvantages others, particularly students who are struggling with the retention and recall of key concepts.

In my memory and cognition class at GSU, we have been studying the pioneers of memory research. I presented a paper exploring the findings of H. Ebbinghaus and his famous “forgetting curve” depicting the natural rate of memory decay. During the session, one of my colleagues shared with me a more recent “Forgetting Curve,” offered by the undergraduate Learning Center at the University of Texas.

The researchers in this study found that students who review new material the same day as they are initially exposed to it have a dramatic increase in retention over their peers who fail to do so.

Perusing PsycInfo, my primary source for peer-reviewed research journals, I have come across a body of research supporting this theory. Repetition and retrieval practice, when timed as close as possible to the initial learning, can dramatically enhance retention.

According to the journal articles, if a student is struggling with retrieval and recall, a powerfully effective strategy is to have the student review all new material within 24 hours of first exposure. How does this work? According to the “multiple stores” theory of memory, information transfers from short term (working memory) into long term memory storage. Effective transfer involves a number of factors: the richness of the encoding process (as referenced above) impacts the transfer as do the number of individual memory traces for specific material and the reinforcement of these memory traces. The act of learning, forgetting, and relearning information reinforces the strength of the long-term memory trace and makes it more likely that a student will be able to recall that material at a later time. If a student strengthens a memory trace through multiple iterations of review and retrieval practice, the information will encode more deeply and deteriorate more slowly.  Accordingly, students will be on a much “flatter” forgetting curve than those who delay their retrieval practice or review.

Practical advice for students

Repetition helps

Each subsequent iteration of retrieval practice and review reinforces the long-term memory trace. If you are working on developing your SAT vocabulary, once you have learned a new SAT vocabulary word for the evening, do not instantly file it away into your “know it” stack. Keep it in the “still working on it” stack, and review it several more times along with your other words. Some of my students have a practice for learning new vocab words.  They lay out a handful of vocabulary words while they are brushing their teeth, and learn 5-10 new words each night. That’s a good start, but it is even better to reinforce the words you have already “learned” and then add novel words.  Use an additive approach. If you successfully learned 5 words on Monday evening, when Tuesday’s review session rolls around, it would serve you to review Monday’s words as well as adding 5 novel words. Keep Monday’s words in the stack for 2-3 review sessions, even if you “know” them.  Sometimes it takes several rounds of repetition and retrieval practice to move things into your long term memory.

Unaided retrieval trumps aided or cued retrieval

When you are doing retrieval practice for vocabulary (or other forms of memorization) it’s important that you see only the word and force yourself to retrieve the definition, as this is what you will be asked to do on the actual test. It’s the act of retrieving the information without cues that deepens the memory trace. Testing effects have continuously been proven to enhance recall. Casually reading through the vocabulary is not nearly as effective for creating a long-term memory as unaided retrieval practice.

The 24-hour rule

If you learn a new vocabulary word or concept in a tutoring session and you want to retain that information, go home and rehearse that word or concept within 24 hours; this will strengthen the trace of the memory and facilitate the transfer from short term to long term memory.

If you are a student who has particular trouble recalling concepts from your sessions, it would be beneficial to set aside 30 minutes each night after each tutoring session to review the concepts you have learned. Schedule that into your calendar and conceptualize the 30 minutes of review as part of the session. The 30 minutes of review may be more important than the session itself!


Applerouth is a trusted test prep and tutoring resource. We combine the science of learning with a thoughtful, student-focused approach to help our clients succeed. Call or email us today at 202-558-5644 or info@applerouth.com.


  • :)

    Hermann Ebbinghaus is a genius.