Spacing Retrieval is More Important than Extra Retrieval

Spacing Retrieval is More Important than Extra Retrieval

Let me phrase those results a different way. Taking the same amount of time and energy that it took to write the normal quiz for a class and just distributing those questions across a couple different quizzes was more beneficial than writing and answering (and grading?) additional quiz questions.

Educators: Quiz your students. Absolutely you should incorporate retrieval practice. Just space it out over time instead of providing blocked weekly quizzes just over that week’s content. But congratulations! You don’t have to do the extra work of writing and grading more quiz questions to get this benefit!

Students: Quiz yourselves and when you do, make sure you’re reviewing old material. Build in frequent study sessions, but you don’t have to double the time you’re spending studying to get great benefits, as long as you’re doing what you should be doing throughout (spaced retrieval).


I started this blog by saying you shouldn’t change your habits on the basis of one study. And then I told you to change your habits on the basis of this study…

This study in housed in a large body of research, making me feel pretty confident about those tips above. That said, there are some things to consider here. This research was done with precalculus engineering students at a university. They’re probably not representative of everyone. Even further, in order to analyze the data, the researchers could only look at students who actually took all of the quizzes (about half the class). Their behavior may have been different (i.e. they may have studied a lot more outside of class), which could influence these results.

Another important result in this study is that increased spacing reduced quiz performance. Even though students remembered more of the material long-term, their initial performance wasn’t great. This is so important. Students are not going to like this. It’s harder than taking a weekly quiz over what they just learned. It’s also important that educators not “punish” students for this reduced initial performance. If we want to encourage students to engage in a behavior at home that is going to lower their grades in class… that is arguably unethical as grades (perhaps unfortunately) determine much of their future success. Educators need to express this to students. They need to understand why they are doing something different and harder than they’ve done before and they need to be provided with the psychological safety to fail early for later gains. In other words, quizzes should be low or no stakes in order to reduce the anxiety involved with what will inevitably be lower initial marks.

Bottom Line

Retrieve old stuff.

No, really. The bottom line here is that you should be utilizing retrieval and you should space it out, but you don’t need to worry about doing so over and over and over again necessarily (although a few times to get that spacing in is necessary). And it’s going to be hard, but that is going to lead to better retention and therefore better performance on the final and in the next class. #worthit


(1) Hopkins, R. F., Lyle, K. B., Hieb, J. L., & Ralston, P. A. S. (2016). Spaced retrieval practice increases college students’ short- and long-term retention of mathematics knowledge. Educational Psychology Review, 28(4), 853-873.

(2) Lyle, K. B., Bego, C. R., Hopkins, R. F., Hieb, J. L., & Ralston, P. A. (2020). How the amount and spacing of retrieval practice affect the short-and long-term retention of mathematics knowledge. Educational Psychology Review, 32(1), 277-295.