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What is the Spacing Effect? (and why you should be using it!)

By: Emily Rae Sabo Wed Dec 20 2023

Hallo! Hoe gaat het? Welcome back, language teachers!

In this article, we’re talking about one of the most well-researched yet under-utilized learning principles: the Spacing Effect! What is it, why does it matter to language learning, and what should you know about it to help your students improve their retention in the language? Well, sem mais demora, let’s get to it!

As a teacher, you want your students to remember the content you teach for more than a unit, a semester, or a school year. Yet how often do you hear students say they forgot everything from the year before? The truth is that we tend to forget things we don’t use — and we remember things that we see multiple times. Enter “the Spacing Effect.” So, what exactly is it?

The Spacing Effect – the phenomenon by which retention of learning content increases when study or review sessions are spaced out, as opposed to done in one sitting.

Graph that says: "Spaced repetition yields better retention"

What this means is that you were right to tell students they should “study a little bit each day – instead of cramming all at once.” Over 100 years of research (Ebbinghaus, 1885; Murre & Dros, 2015) have clearly demonstrated that learning is more effective when exposure is spaced out over time, rather than done all in one sitting. (Cepeda, Pashler, Vul, Wixted, & Rohrer, 2006; Kang, 2016). When it comes to long-term retention, cramming for an exam is never as effective as studying regularly over the course of a semester. With a little planning, you can leverage the benefits of the Spacing Effect to help your students retain the language for longer.

Let’s back up and think about what students are learning when they learn a language. An educated English speaker, for example, knows 20-30k words along with hundreds of idioms and multi-word expressions (Carey, 2015). And one reasonable estimate is that it takes roughly 2hrs/day for 5 years to get half that for any language. That’s a lot of information – so it’s no wonder that forgetting is a natural part of the language learning process! Lucky for us, research into the Spacing Effect provides teachers with insight on how to reduce forgetting and increase retention.

To that end, it’s helpful to think of language learning like building a sandcastle. You build the foundation. But if you don’t regularly reinforce the base, it can start to crumble. You can help your students reinforce their language base by introducing Spaced Repetition into your class structure. It’s worth mentioning that Spaced Repetition helps increase retention length for many kinds of learning content: math, physics, and importantly, for our purposes here, languages. In some circumstances, spaced studying (relative to single-study sessions of the same overall length) has been shown to double a learner’s retention rate!

A sand castle

3 main things you need to know about the Spacing Effect:

  • What is the  “Forgetting Curve?”
    This is a simple negative-sloping curve by which learning content loses its retrieval strength over time. It’s educational psychology’s way of saying “Use it or Lose it.” Spaced repetition flattens this curve thereby maximizing retention. Thinking about student learning in terms of the forgetting curve can help you structure your lessons, and help students set goals and stay motivated. Some students are visual learners, so seeing the retention loss and gains on a simple graph can be a powerful rhetorical device to have in your back pocket when talking about the Spacing Effect.

  • What should you say to a student who says that cramming works for them?
    They might be right – but they’re likely not seeing the whole picture. It’s true that students can perform equally well on a test when they cram and when they study using spaced repetition. But the real difference comes later: when a student uses spaced repetition to study, they will remember the information for longer after test day. So, it’s really a conversation about their longer-term learning goals with the language. Do they want to be able to use this language after the course ends? Are they taking the next course level in the language curriculum? If they’re taking Spanish II next semester and don’t want to be starting from scratch then, they’re much better off spacing out their studying. If you’d like a fun and easy worksheet to help your students reflect on their language goals, check out our FREE Setting Good Goals worksheet!

  • How long should the gaps be between study sessions for optimal retention?
    Here’s what we know. First — and this is the most important piece to remember — the gaps between study sessions should be shorter at first and the longer as time goes on. From there, it really all comes down to (1) how quickly does the information need to be learned (when is the test; shorter gaps should generally lead to faster acquisition, since more material is presented in a shorter period of time) and (2) how long does the student want to retain the information (how long after the test or after the course ends; longer gaps lead to longer retention, at least up to a point) (Kang, Lindsey, Mozer, & Pashler, 2014). Now, let’s get concrete about it. Spaced repetition schedules are generally created with days as the unit of spacing in order to capitalize on the role of memory consolidation during sleep (Rasch & Born, 2013). Let’s imagine a student wants to prepare for a travel words themed vocabulary test that’s coming up in a week. The student knows about the Spacing Effect, so instead of doing a late-night cram session in one sitting, they’re going to use spaced repetition and break their study session into two study sessions on two separate days. Now, what’s the optimal gap for maximizing retention for a test that is a week away? The research is pretty clear on this. Given two practice sessions, the student should space their study sessions apart by about 2 days. Now let’s think bigger. What about if the student wants to maximize their retention of those travel-related words for a year? Maybe that’s when the AP test is, or maybe they have a trip abroad planned…etc. The optimal gap for maximizing retention for a year requires sessions to be spaced apart by roughly 25 days on average (Cepeda et al., 2008, 2009). But remember, that’s 25 days on average. For optimal results the gaps between study sessions should be shorter at first and longer as time goes on. So, maybe after studying a vocab set for the first time, they revisit it once every other day for a week, then once a week for a month, and then once a month for the rest of the year.

If you’re a teacher who uses the Mango Languages app with your students, then you already know that Spaced Repetition is built into the app’s review system. When your students use the app, it tracks what words and grammar points they haven’t seen in a while and reinforces them with practice opportunities, automatically introduced based on our Spaced Repetition algorithm.

To recap, here are the talking points to keep in your back pocket when talking about the Spacing Effect with your students:

  • The Spacing Effect is the phenomenon by which long-term retention improves when study or review sessions are spaced out, as opposed to done all in one sitting.

  • The “Forgetting Curve.” This is a simple negative-sloping curve by which learning content loses its retrieval strength over time. It’s educational psychology’s way of saying “Use it or Lose it.” Spaced Repetition flattens this curve thereby maximizing retention.

  • The study schedule for optimal retention will incorporate shorter gaps between study sessions up front, followed by longer gaps later. In practical terms, the two factors that will ultimately help a student determine their optimal study schedule are (1) how far away the test is and (2) how long after that test they want to retain the information.

Thanks for reading!

Dáág! We look forward to seeing you back here for our next article!

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Want to explore more of the research underlying this article?

  • Ullman, M. T., & Lovelett, J. T. (2018). Implications of the declarative/procedural model for improving second language learning: The role of memory enhancement techniques. Second language research34(1), 39-65. | This is a nice

  • Carey, B. (2015). How we learn: The surprising truth about when, where, and why it happens. Random House Trade Paperbacks. Check out Chapter 4 of Ben Carey’s book How We Learn, titled “Spacing Out: The Advantage of Breaking Up Study Time.” It’s a great read!

Wondering what languages were used in this article?

  • English | Base language for the article

  • Dutch | Hallo! Hoe gaat het? is ‘Hello! How are you? (lit. ‘Hello! How goes it?) and Dáág is ‘Goodbye!’

  • Brazilian Portuguese | Sem mais demora is ‘without further ado’ (lit. ‘without more delay’)

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