Roddy Roediger is a psychology professor at Washington University in St. Louis and runs the school’s Memory Lab.

This phenomenon — testing yourself on an idea or concept to help you remember it — is called the “testing effect” or “retrieval practice.” People have known about the idea for centuries. Sir Francis Bacon mentioned it, as did the psychologist William James. In 350 BCE, Aristotle wrote that “exercise in repeatedly recalling a thing strengthens the memory.”

Another theory is that information goes into our brains attached to context.

Sobel realized that his students were studying in exactly the wrong way, by rereading their notes the night before his two exams.

A vastly better model, Sobel thought, would be one where he essentially forced his students to retrieve knowledge over and over again throughout the course.
So, every semester, instead of two exams, he started giving his students nine quizzes.

Sobel has tried to talk to his colleagues about the results he was seeing with quizzing, but he says most of them aren’t interested in switching from a few exams to multiple quizzes. “University faculty are considered very smart, but are also very conservative,” Sobel said. “We don’t like to change our ways.”