The Forgetting Curve & American Education

Psychologist Herman Ebbinghaus discovered that without reinforcement or connection to previous knowledge “roughly 56% of information is forgotten in one hour, 66% after a day, and 75% after six days.”  He called this the forgetting curve.

In classrooms, we see this curve in practice directly after a comprehension check or test.  Students hold on to information for long enough to prove themselves in a testing scenario, and then quickly forget much of the information.  It’s frustrating that our current system still focuses on our ability to store and retrieve information, but fails to teach in a way that will make lessons stick, or to develop students’ capacity for retaining material.

Lessons from Neuroscience

However, science has recently unearthed some keys to memory and recall. In 2015, Neuroscientists at MIT, led by Troy Littleton and Richard Cho, discovered that not only postsynaptic, but presynaptic neurons are important for the process of remembering.  Through a series of tests on flies, they managed to recreate small, previously thought to be irrelevant, actions in the presynaptic neuron. Afterward, they noticed a difference in the connection, or synapse, between a presynaptic and postsynaptic neuron.  Richard Cho stated, “Machinery in the presynaptic terminal can be modified in a very acute manner to drive certain forms of plasticity which can be really important… in development… and behavioral processes like learning and memory.”

This study at MIT calls for a different outlook on a specific type of neuroplasticity, or the ability of the brain to change throughout one’s life.  We now know that both neurons and synapses are adaptable, due to the signals to one another. If signals are sent enough, connections can turn from dirt roads into highways.  

Young people’s brains need to be cultivated properly for them to have the tools they need for success later on.  If a student’s mind is not stimulated consistently, and if habits are not created at a young age, then the brain will have trouble storing important information.  But what is the proper way to stimulate and prepare young minds? Let’s return to Ebbinghaus’s work: recall that 56 percent of information is forgotten in one hour without proper reinforcement or connection to previous knowledge. In other words, new learning must build on previous knowledge, and reinforcement is crucial to the learning process.   

Building on Previous Knowledge: The Willow Analogy for Creating Curriculum

What makes it so that we can’t think of that one thing we are trying to remember? Or when we know information, but can’t recall it effectively? 

To understand how we come to this problem, imagine a student’s brain is a willow tree.  The brainstem is the trunk and all the branches and leaves make up the neurons and squishy, smart matter.  Pretend you are a bug, living on the trunk. You are trying to get to a specific piece of fruit on the tip of the tree’s branches.  Would you be able to find your way to the exact spot, just by picking left or right, up or down, at every fork in the road? It would most likely prove to be an impossible task.

Yet if you started at the tip of the branches, could you make your way back to the trunk? It’d prove much easier - you’d know the direction you’re headed (towards basic, core knowledge), and you’d be able to see how smaller branches broke off larger, foundational ones. In a well-connected brain, it is easy to trace back from the most obscure pieces of one’s knowledge to their core skills, learned early on. 

The willow tree analogy shows why it’s best to properly connect every lesson to one before it, rather than one after it.  By working backward, we ensure that all new information connects to previous knowledge, thus drastically mitigating the forgetting curve.  If we start at an end-point and move backward, we can clearly see what is necessary to teach to younger students, so that more complex curriculum can be learned later. As educators, we build the foundation of our youth’s minds.  If each branch is not carefully connected to the branch before it, the mind will become a muddled mess.

Here is an example of how we design curriculum:

Step 1:  Identify a high demand, not automatable, and relevant job. As an example, financial analysts will become increasingly important in our world.

Step 2:  Identify necessary, topic-specific prerequisites for the role. A financial analyst needs to understand profit and debt accumulate exponentially.

Step 3:  Create curriculum by moving backward. We move from the most complex to least complex topics.

• 14. Applying formulas for exponential growth or decay with variables for missing values

• 13. Understanding the difference between linear and exponential equations

• 12. Application of knowledge to create equations using variables

• 11. Advanced extraction of expressions and equations form word problems

• 10. Variable isolation

• 9. Reversing order of operations

• 8. Balancing an equation

• 7. Order of operations

• 6. Extraction of expressions and equations from word problems

• 5. Expressions vs equations

• 4. Square roots and exponents

• 3. Division and multiplication

• 2. Addition and subtraction

• 1. Count up and count down

This is a simplified version of a curriculum tree line.  When moving from the bottom of this list to the top, we should all be able to understand why a 6th grader cannot be thrown variable isolation problems when she doesn’t yet understand balancing an equation.  And yet, that’s what is happening in public education today. Public school curriculum is often so focused on introducing new content, that it neglects to realize students didn’t have the foundation to retain it. We recently saw 3 classes in 6th grade at a local public school assign homework that required lessons not previously taught. This kind of curriculum is unfair to kids.

In this situation, is there any way for the children to connect the current lesson to the one before it?  No. So how will they internalize the material? Most likely, they won’t. The consequence will be forgetting 66% of the information by the end of the day.  Good luck trying to get that lesson to stick.

Reinforcing Information

Good curriculum always builds on previous knowledge, so new information is easy to grasp and retain. But the forgetting curve has two key drivers. Reinforcement is also a necessary component in quality teaching.

Reinforcing means reviewing not just before a test, but also reviewing after.  For example, one of the most commonly forgotten lessons in Elementary Math is subtracting over multiple repeated zeros. Students tend to forget the lesson after the test is taken, and when the topic comes up again in a word problem a year or two later, it becomes an issue.  

So how do we assure retention?  A fantastic method that can be used for long-term retention calls for individualized curriculum.  If a child’s retention is kept track of, it is easy to extend the period of time between retention checks.  For example, we teach our second graders to subtract over multiple zeroes. If they do it correctly, the next time the exercise is repeated is in two days, then three days, etc.  The time between retention checks grows. On the flip side, if another student fails the first retention check, the error is addressed, and the duration between retention checks is shortened, until they begin to complete the checks accurately. We never stop our retention checks just because we’ve moved onto another “unit”, or introduced new material, especially if a student has failed to internalize the material. We always integrate the retention of old material with the introduction of new material. 

Summer Months: An Enemy to Retention

Public school curriculum often acts as an enemy to retention, as curriculum is rarely reviewed, except before a standardized test. However, public schooling’s greatest assault to retention is not poorly designed curriculum. Instead, it’s summer vacation. 

The normal summer break is a great example of how little research is actually implemented by public and private schools worldwide.  Allowing a two-month hiatus from academics loses not just two months of material, but two months of reinforcement of old material. This allows for the “summer slide”, a phenomenon in which the average student slides back 2 ½ months worth of skills during the summer. In other words, in September, students’ skill levels are closer to where they were at the beginning of April, not the middle of June. This is not only detrimental to a child’s progress, it also defeats them emotionally: students lose confidence when they have trouble performing actions that were previously simple. Stopping and restarting an education is counterproductive to retention and confidence. We need to make sure that we continue to challenge a child’s mind for the sake of retention and to prevent deceleration.

Now we can understand why the specialized high schools test administer the test in the Fall, instead of the Spring. Although the Fall is further from the student’s matriculation, testing in the Fall allows for a test of initiative and the ability to retain over time. The student is expected to have taken the initiative after school, during weekends, and summers, so that she is ahead of peers.

Summer Head Start is a program that focuses on English, writing, grammar, and mathematics from the previous school year, as well as next year’s curriculum.  This is a perfect way to make sure your child starts off strong, and is ahead of the game the whole school year. Two months of structured and individualized curriculum, every year, can add up to an extra year of schoolwork by 6th grade, not to mention the prevention of the summer slide.  Imagine your child having an over an extra year of learning by 6th grade. Additionally, our students all move at their own pace. Some move ahead of grade level, while others get the extra help they need to solidify the past year’s content. With all of our students, we review the material with them until it is understood in a way that they can retain and recall.

- Mr. S