In a piece in The New York Times Magazine's recent education issue with the provocative headline "Why Flunking Exams is Actually a Good Thing," science reporter Benedict Carey delved into the science of "pretesting," or using testing as a way to study and learn. The idea suggests that failing a test question is one of the best ways to stimulate our brains to learn.

The basic insight is as powerful as it is surprising: Testing might be the key to studying, rather than the other way around. As it turns out, a test is not only a measurement tool. It’s a way of enriching and altering memory.

Why does testing work in this way? Because it's difficult for our brains to understand what we actually know until we're asked.

The problem [with other study methods] is that we have misjudged the depth of what we know. We are duped by a misperception of “fluency,” believing that because facts or formulas or arguments are easy to remember right now, they will remain that way tomorrow or the next day. This fluency illusion is so strong that, once we feel we have some topic or assignment down, we assume that further study won’t strengthen our memory of the material. We move on, forgetting that we forget.

The learning-through-testing idea is good to know about if you're learning words on In fact, our proven method for faster, more efficient vocabulary instruction is based in large part on how effective pretesting can be. Here, we'll break down some of the ideas Carey presents in order to show how they impact word learning. 

1. Learning-Though-Testing has a Long History Because it Makes Intuitive Sense

In the Times piece, Carey, who is the author of How We Learn: The Surprising Truth About When, Where and Why It Happens (to be published by Random House this month) traces the history of the learning-through-testing, which is a long one, as the idea makes intuitive sense.

In 1620, the philosopher Francis Bacon wrote, “If you read a piece of text through twenty times, you will not learn it by heart so easily as if you read it ten times while attempting to recite it from time to time and consulting the text when your memory fails.”…Scientific confirmation of this principle began in 1916, [leading to the insight that pretesting was] not merely a study tip for memorization; it was nothing less than a form of self-examination.…

The testing effect, as it’s known, is now well established, and it opens a window on the alchemy of memory itself. “Retrieving a fact is not like opening a computer file,” says Henry Roediger III, a psychologist at Washington University in St. Louis, who, with Jeffrey Karpicke, now at Purdue University, has established the effect’s lasting power. “It alters what we remember and changes how we subsequently organize that knowledge in our brain.”

At, we didn't come up with the idea of teaching through testing, but we did employ that theory thoughtfully, combining it with research about spaced repetition to create a formula where we're asking questions about words at carefully determined intervals to ensure you're learning them as thoroughly and as efficiently as possible. (Read more about how we learn words by building neural pathways in the brain here.)

2. Testing Can Increase Learning By Ten Percent

The impetus for Carey's article was a new study conducted by the U.C.L.A. psychologist Elizabeth Ligon Bjork showing that "pretesting raised performance on final-exam questions by an average of 10 percent," which, Carey points out, is "far from a magic memory pill — but 10 percent, as we all know, can often translate to a letter grade."

[Bjork] and Nicholas Soderstrom, a postdoc, gave the entire class of more than 300 students a short pretest, all multiple-choice questions, immediately before the start of some lectures but not others. “We wanted to see whether students would better remember and understand material from lectures preceded by a pretest than from lectures not preceded by a pretest,” Soderstrom said.

To answer that, Bjork and Soderstrom did something clever on a cumulative final exam, which was given at the end of the course. Namely, they included on it questions that were related to the pretest ones as well as questions that were not. “If pretesting helps, then students should do better on related questions during a later exam than on questions about material we covered in the lectures but was not pretested,” Bjork said. She and Soderstrom would compare students’ scores on pretest-­related questions with their scores on nonpretested ones, to see if there was any difference.

One of the promises makes to word learners is that we will not waste your time. We are able to deliver on that promise not only because our adaptive learning game target words you don't know, but also because it uses testing as a teaching tool. Instead of letter grades, you earn points and achievements, but you can expect all that pretesting to deliver a boost in your vocabulary retention and learning speed. 

3. Testing is Particularly Well Adapted to Word Learning

When discussing the limitations of pretesting, Carey brings up an interesting point about ways in which all pretest questions are not created equal:  

Bjork’s experiment suggests that pretesting serves to prime the brain, predisposing it to absorb new information.…To review, memory builds on itself in ways we don’t usually notice. Retrieval — i.e. remembering — is a different mental act than straight studying; the brain is digging out a fact, together with a network of associations, which alters and enriches how that network is subsequently re-stored. But guessing is distinct from both study and retrieval. It too will reshape our mental networks by embedding unfamiliar concepts (the lend-lease program, the confirmation bias, the superego) into questions we at least partly comprehend (“Name one psychological phenomenon that skews our evaluation of evidence”). Even if the question is not entirely clear and its solution unknown, a guess will in itself begin to link the questions to possible answers. And those networks light up like Christmas lights when we hear the concepts again.

And here is where pretesting shows its likely limitations: A prefinal for an intro class in Arabic or Chinese could be a wash, because the notations and characters are entirely alien. There’s no scaffolding of familiar language to work with — no existing network in which to situate the new symbols — before we make a guess. We are truly lost, with no recognizable landmark. The research thus far suggests that prefinals will be much more useful in humanities courses and social-science disciplines in which unfamiliar concepts are at least embedded in language we can parse.

How many times have you seen a word and believed you know what it means, only to realize when trying to articulate its definition that your knowledge is incomplete or "fuzzy"? This might make you feel stupid but don't worry. You're simply experiencing the way word learning works naturally. Our brain absorbs language in a process that takes place over multiple encounters with that word. The more often we see it, the more likely we are to remember it.

During the phase of this process when the word feels familiar but we haven't learned it all the way, the multiple choice questions in the game offer precisely the kind of hints or "scaffolding of familiar language" you need to make an educated guess. And the process of making that educated guess is exactly what your brain needs to be doing in order to more fully learn and remember that word.