Large numbers of studies have demonstrated the benefits of repeated testing. Requiring learners to retrieve and process previously learned information reinforces what they know and strengthens the neural connections, leading to long term retention.
Most of these studies use classic experimental design. They split a learning group in two: One group studies in the normal way (rereading typically); the other is required to answer test questions or write down everything they remember about the subject. The studies almost always show that the group that was repeatedly tested outperformed the group that studied in the normal manner.
I was intrigued when I came across a study from 2011 that took a different approach. They compared the learners against themselves, rather than against a control group. How did they do that?
In the study (McDaniel, Agarwal, Huelser, McDermott, & Roediger, 2011), the authors had middle school students take frequent no stakes quizzes (no consequences) during a course. But instead of quizzing them on all the material, they only quizzed them on a subset of the material. On the final exam, which tested all of the content, the students performed 13 to 25% better on the material they had been quizzed on than the material they had not.
You can quiz using a straightforward exam-like quiz, embed the quizzing in an adaptive questioning exercise, or gamify the experience. It doesn’t matter. The bottom line is the same: Quizzing enhances long term retention. There is no doubt about it.