I came of age during an epoch known as the Great Testing Tyranny. It was a rare school day that we didn't face a quiz or a test or an exam of one kind or another, and sometimes we weren't even warned in advance. We memorized multiplication tables and Latin vocabulary words and historical dates and passages from Shakespeare, and then we proved ourselves on test day. Some were life-altering tests; always under the pressure of the clock, with rigorous rules: No. 2 pencils only, erase completely, stray marks may be misinterpreted as wrong answers.

It was a terrifying time.

The popularity of testing seems to ebb and flow. The practice fell into a long period of disrepute after the Great Testing Tyranny, fueled by fears that we were blunting our children's creativity. Then the No Child Left Behind Act ushered in another testing frenzy, and we now appear to be entering yet another period of backlash. Much of this to-and-fro is political, of course. But often lost in this rhetoric is the most basic question of all: Does it work? Do kids who are tested a lot learn more or less than kids who are not?

Psychologists and educators are very interested in these questions, and in the related question: What's the best way to study? Traditionally, tests have been viewed and used as mere assessment tools—a way to measure whether or not students are progressing as they should be. But two psychologists—Henry Roediger of Washington University and Jeffrey Karpicke of Purdue—have been challenging this conventional wisdom. They believe that quizzes and tests and exams are much more than measurement devices; that indeed testing might be a cognitive cornerstone of the learning process. They have been conducting an elaborate series of experiments to sort out the complex interplay of studying and testing and learning.

Here is a typical experiment, one many of us can relate to. Say you're going on vacation to a foreign country, and you want to talk to the local people in their native language. It's a worthy goal, and you really have to memorize words and phrases to do it; there's no way around it. The experiment simulated this real-life challenge, imagining a trip to a Swahili-speaking nation, say Tanzania. A group of volunteers were given a list of 40 Swahili-English word pairs: Mashua is the word for boat; yai means egg, and so forth. They were told to learn them as quickly as possible.

So what's your best strategy for learning a little Swahili? Picture yourself with flashcards. There are various ways you could do a mix of studying and self-testing; you could use most of your time for traditional studying, or you could give more time to self-testing, or some combination of the two. Most kids in school are advised that the most efficient way to learn is to study until you get a word right, then move on.