The technology we have at our disposal is nothing short of amazing. With internet-connected smartphones, we can get answers to questions that would have taken days or months in the past. Our personal computers, and even the latest smartphones, have the power to perform mind-bending calculations that previously required entire rooms filled with banks of computers working together.

Yet even with all this amazing technology at our fingertips, we must still learn and memorize new information, and simple flashcards remain one of the best ways to do this.

How flashcards help learning

We get it. Studying takes a lot of time.

We only get 24 hours every day, and you’d like to spend those hours doing things like earning money, doing fun things with friends, writing your bestselling novel, or any number of other pursuits. How can you spend the least amount of time studying so you can still learn and retain the optimum amount of information?

There is a way to achieve this, and it’s simpler than you might imagine. It’s called spaced repetition. Its core principle involves introducing time intervals between your study sessions. It can help you memorize and recall more information even if you spend fewer hours studying.

Spaced repetition may be the most powerful known technique to improve mental recall of what you study.

Why is spaced repetition so powerful? It leverages a memory phenomenon called the spacing effect, which describes how your brains learn more effectively when your learning is spaced out over time.

It essentially works like this. Think of learning as building something, like a brick wall or other structure. Stack bricks too fast without letting the mortar dry and the wall will crumble. Spacing out your learning is like giving your “mental mortar” time to dry between study sessions.

Over time, many theories about memory, learning, and forgetting have been developed. One of the more recent theories is called the Forget to Learn theory, which helps explain why we retain some memories while others seem to fade away.

The first principle of this theory is that our memory has two strengths:

  • Storage strength of a memory doesn’t fade over time. Once we put information into it and the brain identifies it to have some level of importance, it remains stored. Storage strength can only be improved through repeated recall or use.
  • Retrieval strength, the ability to access the memory, does fade over time. It’s a bit fickle, doesn’t hold as much as storage strength, and needs to be maintained regularly.

The result of all this is that forgetting is an accessibility problem: the memory is there, but we can’t locate it.

The second principle of the Forget to Learn theory is: The greater the drop in retrieval strength, the greater the increase in learning when the memory is later accessed. In other words, according to researcher Robert Bjork, the best time to relearn something is just before you are about to forget it.

It’s a bit like exercising a muscle. When you exercise, the muscle is taxed and broken down a bit. You then eat, sleep, and rest, which lets the muscle recover and grow. Essentially, you stress your body, let it rest and recover, adapt, and become a bit stronger the next time. Yet if you exercised the same muscle every day, it wouldn’t recover and wouldn’t grow.

Learning essentially follows a similar model. Learning causes mental stress, from which you need to recover to let the new information take root in your memory. Like your muscles, you can overwork your memory by studying too long. Spacing out your study sessions helps your memory rest and recover, and could even support overlearning, a more niche learning strategy.

If spacing out study sessions is good, is there any optimal spacing? Several studies have been performed to answer this question. A 2008 study asked this question for a given test date. It found that the optimal gap between study sessions increases with how far out in time the test is. This spacing also helps maintain your focus when studying, by giving your brain a much-needed break.

If you have a test in one week, then have your first study session today, the next tomorrow, or the next day, then maybe a third session the day before the test. These are all approximate gaps and must be scaled depending on how far out the test is. Tests at further time points need longer gaps between study sessions.

How can you apply optimal study spacing? That’s right: simple, old-school, paper flashcards.

4 ways to use the flashcards revision technique

Flashcards help with learning by breaking information into small pieces to which you can apply spaced learning. Generally, flashcards are best used for pieces of information like words, phrases, definitions, and symbols.

As a bonus, the physical act of writing flashcards can help with information recall. Writing is better than typing in this instance because it activates the memory-encoding parts of your brain.

Here are some more detailed examples of how flashcards help with learning:


The flashcards revision technique can be used to learn foreign words and phrases.

Write an English word on one side of a card (“cheese”), then its Spanish word on the other side of the card (“queso”). Do this for twenty words. Shuffle the cards, then go through each Spanish word and try to remember its English word. Then switch and repeat this but look at the English words first and try to recall each Spanish word. Language learning apps like Duolingo and Memrise incorporate this flashcards revision technique.

Medical terms

Medical terminology is some of the most difficult to memorize. A set of effective flashcards can be created to help learn medical terms for med school or even a biology class. Take twenty cards and write a medical term on each. Flip each card over and write a short definition on the back. Go through each medical term and try to remember its definition. Then flip it around, going through each definition and trying to come up with the term. This flashcards revision technique can help you learn unfamiliar technical terms quickly.

Musical notes

A set of flashcards can be made to help you learn musical notes as well!

Following the examples above, start with ten or twenty cards and on one side of each card, write the symbols that describe a specific musical note. On the opposite side of each card, write the name of the note. Go through the symbol side of each card and try to remember the note’s name. Then switch, going through each name and in a notebook or blank music sheet, write down the note.

Data science

This flashcards revision technique can even be applied to more niche subjects like data science, programming and engineering. Googling technical terms is often an acceptable approach, but in some cases, you will need to have your own recollection.

For example, machine learning courses teach you about a variety of algorithms and concepts that you’ll need to remember for later. Employing the flashcards revision technique is one of the easiest ways to memorise them!

Effective flashcards with the Leitner system

While spaced learning with optimized intervals can be effective, you constantly have millions of different little learning curves happening simultaneously, each of which has its own rate in which you are learning—and forgetting—information.

While it would be impossible to apply spaced repetition to each of these learning curves, you can target specific learning curves for information that you want or need to learn.

How flashcards help learning by using the Leitner System
The Leitner System (via ResearchGate)

German scientist Sebastian Leitner created an improved flashcards revision technique to help address this. The Leitner system uses several boxes to track when you need to study each flashcard. This system has three rules:

  1. Every card starts in Box 1
  2. When you get a card right, you move it forward a box
  3. If you get the card wrong, you move it back a box

Spaced learning is applied, resulting in a study schedule like this:

  • Box 1 – Every day
  • Box 2 – Every 2 days
  • Box 3 – Every 4 days
  • Box 4 – Every 9 days
  • Box 5 – Every 14 days

Buy your supplies, create your cards, set up a schedule, and use the Leitner system to improve your study sessions!

In summary

While we literally have amazing technology at our fingers that allows us to find almost any information instantly, there are still things we need to memorize. For these situations, the tried-and-true use of the flashcards revision technique is still one of the best methods.

Fully effective flashcards utilize the principle of spaced repetition, which optimizes our brain’s ideal cycle of learning and forgetting. Flashcards are best used to memorize pieces of information like words, definitions, and symbols. The Leitner system is a simple, concise method of using flashcards applied to an optimized spaced repetition schedule.

Make a set of flashcards and try the Leitner system today and you might find that your studying and memory improve significantly!