By Daniel Willingham
If a student believes that he knows material, he will likely divert attention elsewhere; he will stop listening, reading, working, or participating.

Mentally “checking out” is never a good choice for students, but all the more so when they disengage because they think they know material that, in fact, they do not know.

The feeling of knowing becomes a problem if you have the feeling without the knowing. There are some very obvious ways in which students can reach this unfortunate situation in a school setting.

Here are several common ones:

1. Rereading
To prepare for an examination, a student rereads her class notes and textbook. Along the way, she encounters familiar terms (“familiar” as in she knows she’s heard these terms before), and indeed they become even more familiar to her as she rereads. She thinks, “Yes, I’ve seen this, I know this, I understand this.” But feeling that you understand material as it is presented to you is not the same as being able to recount it yourself.

As teachers know, this gap between feeling that you know and genuine recollection can cause great frustration. I have frequently had exchanges in which one of my students protests that despite a low test grade, he or she really knew the material. When I ask a general question or two, the student struggles to answer and ends up sputtering, “I can’t exactly explain it, but I know it!” Invariably, a student with this problem has spent a great deal of time reading over the course material, yielding a lot of familiarity, but not the necessary and richer recollective knowledge.

2. Shallow Processing
A teacher may prepare an excellent lesson containing a good deal of deep meaning. But this deep meaning will only reside in a student’s memory if the student has actively thought about that deep meaning(see “Students Remember...What They Think About,” American Educator, Summer 2003).

Let’s say, for example, that a teacher has prepared a lesson on the European settlement of Australia and on the meaningful issue of whether that settlement should be viewed as a colonization or invasion. But, let’s say that a given student did not process and retain the deep meaning intended by the lesson. He did absorb key terms like “Captain Cook” and “Aborigines.” His familiarity with these key terms could mislead him into believing he was ready for a test on the subject.

3. Recollecting Related Information
Sometimes students know a lot of information related to the target topic, and that makes them feel as though they know the target information. (This is analogous to the subjects in the experiment who knew the names of many composers and so felt that they knew who composed Swan Lake.)

Suppose that a fifth-grade class spent three weeks studying weather systems, including studying weather maps, collecting local data, keeping a weather journal, learning about catastrophic weather events like hurricanes, and so on. In preparation for a test, the teacher says that there will be a question on how meteorologists use weather maps to predict hurricanes. When the student hears “weather map,” she might recall such superficial information as that they are color coded, that they include temperature information, and so on; she feels she knows about weather maps and doesn’t study further.

In fact, she hasn’t yet come to understand the core issue — how weather maps are used to predict weather. But her general familiarity with the maps has tricked her into believing she had the necessary knowledge when she didn’t. (Ironically, the problem of recollecting related information is most likely to occur when a student has mastered a good deal of material on the general topic; that is, he’s mastered related material, but not the target material. It’s the knowledge of the related material that creates the feeling of knowing.)

Cognitive science research confirms teachers’ impressions that students do not always know what they think they know. It also shows where this false sense of knowledge comes from and helps us imagine the kinds of teaching and learning activities that could minimize this problem.

In particular, teachers can help students test their own knowledge in ways that provide more accurate assessments of what they really know — which enables students to better judge when they have mastered material and when (and where) more work is required.