Spaced Practice in the Classroom

Spaced Practice in the Classroom

How Podsie saved a teacher one month of review in his classroom.

When my students bombed their first semester exam, it shocked me. It was my second year of teaching eighth grade math, and unlike the previous year, my students had actually done well on the exit tickets and tests up to that point. However, my students seemed to have forgotten everything.

The next semester, I made a concerted effort to carve out time for review, but it was tedious, and I never knew which specific topics to review, and how often to review each topic.

Years later when I was no longer a teacher, I found out that there was actually a science behind the best way to review, and that there was also a large body of research to back it up.

Ebbinghaus and the Forgetting Curve

This body of research goes as far back as the 1880s, when a German psychologist named Hermann Ebbinghaus mapped out memory and how we forget over time.

Forgetting Curve

In his model of memory, Ebbignhaus stated that when content is first learned, without review, memory of that content deteriorates quickly. However, with each subsequent review and retrieval of that information, the memory becomes more durable, and over time, less and less review is required to keep retention fresh.

When I first learned about this, I felt an "Aha!" moment as Ebbinghaus broke down exactly why my students struggled when I was teaching.

For me, because planning out new lessons was already such a tough process, I never had enough time to adequately review throughout the school year. Instead, every year in March, I dedicated an entire month to review all of the content before the state exam. In fact, several lower-performing districts encouraged students and teachers to have “review weeks” to cram review before state assessments. We would power through countless hours of material that students had already "learned", but it never stuck as well as I would have liked.

Ebbinghaus proposed something that I had always intuitively known, but failed to put into practice in my own classroom: spreading out review over time is much more effective than cramming it all into one session.

More Research

Since Ebbinghuas, several researchers have fleshed out this idea of the forgetting curve and spaced review.

To start, John Dunlosky, a professor of psychological sciences at Kent State University, and others broke down 10 different learning techniques, including common practices like re-reading and highlighting, and found that spaced review was one of the most effective ways to learn and retain knowledge and skills.

Meanwhile, Sean Kang, a cognitive psychologist at the University of Melbourne, highlighted spaced review as a highly effective learning technique that does not require more time and drastic changes to the classroom.

Specifically, he states:

Incorporating spaced practice into education can be a cost-effective approach— learning becomes more durable in the same amount of time (relative to massed practice), and this can lead to future savings because less time needs to be spent on relearning content that has been forgotten, leaving more time for other productive learning activities (e.g., higher order analysis, application of knowledge). In short, spaced practice enhances the efficacy and efficiency of learning, and it holds great promise as an educational tool.

In a different paper, Robert Lindsey, another research scientist and now the founder of Imagen Technologies, and others also assessed the efficacy of a computer program that personalized review for each student over time. In this study, personalized spaced review improved retention by 16.5%!

The more research I read, the more I was perplexed —perplexed as to why I hadn't learned about this research-backed learning technique while I was teaching. I had sat through countless hours of professional development and undergone a long certification process, but I had never once heard about how to maximize learning in my classroom through spaced review.

Clearly, there was a gap between research and practical application, and I wanted to see if there was a way to fill that gap.

Spacing in the Classroom

So how would spaced review work in the classroom?

After I learned about spaced review, I shared it with my best friend, Chris, who is currently a science teacher in Texas. He also dug into the research and was excited to try it out in his classroom the next school year. He did a deep dive into all of the learning tools available to help him facilitate spaced review in the classroom.

At that time, there were two teachers who had written blog posts about implementing spaced review in the classroom:

  1. Why Can’t They Remember This From Last Y??? Help Students Remember Key Information: Spaced Repetition Software (SRS).
  2. A Year of Spaced Repetition Software in the Classroom

Both used Anki, a popular spaced review app, to manage the spacing of the materials. However, because Anki was designed for individuals to study on their own, and not for a classroom of students, both teachers used Anki in a way that wasn't personalized to each student's needs.

In other words, each student in the class would study the same question, regardless of whether or not that was actually the question each specific student needed to review. For Chris, that seemed suboptimal, especially since his students had an extremely wide range of skill levels: what student A needed to review was likely to be extremely different than what student B needed to review.

Naturally, he then turned to explore other apps that were designed for classrooms. To his disappointment, he found that while almost all of these apps did a great job in quizzing students in engaging ways, none actually employed spacing to ensure student retention of the information.

Ultimately, it seemed that what Sean Kang articulated in his paper was true:

Despite over a century of research findings demonstrating the spacing effect, however, it does not have widespread application in the classroom. The spacing effect is “a case study in the failure to apply the results of psychological research” (Dempster, 1988, p. 627).

Despite a substantial amount of evidence behind spaced review, not only was spacing not frequently applied, but there was also no easy way to implement it in the classroom.

At Podsie, we're trying to fill that gap, and we're building an app that's hyper focused on making it easy to implement personalized spaced review in the classroom. With Podsie, Chris creates an exit ticket assignment of around 5-8 questions that assesses the content that students learned that day. When students complete a question, the question goes into that student's personal deck.

Each student's personal deck is powered by a spacing algorithm that determines when the student should review a question again. Then, Chris gives his students 10 minutes in the beginning of class to complete every question that is due in their personal decks, ensuring that each student reviews exactly what they should be reviewing on that day.

Traditionally, Chris had also carved out a month to review before the state test. However, this year, even with distance learning, the spaced review has been so effective for him, that he's decided to completely cut out that month of review. This means that he's no longer pressed to move at a blistering pace just to ensure that there is time for review.

So far, Chris has been part of a beta release of Podsie that's been going really well. Before we launch our full public release, we want to hear from more teachers. We're curious to hear, if you're a teacher, have you tried spacing in the classroom? If so, how'd you do it, and how did it work?

Please feel free to get in touch with us at; we would love to chat!