Imagine an eleventh grader named Molly Bloom sits down at the desk in her room and takes an SAT II Physics practice test. She’s a very bright young woman and gets only one question wrong. Molly checks her answers and then jumps from her chair and does a little dance that would be embarrassing if anyone else were around to see her.

After Molly’s understandable euphoria passes, she begins to wonder which question she got wrong. She discovers that the question dealt with optics. Looking over the question, Molly at first thinks the test writers made a mistake and that she was right, but then she realizes that she answered the question wrong because she had assumed the focal point of a diverging lens would have a positive value, when in fact it has a negative value. In thinking about the question, Molly realizes she didn’t have a good grasp on which kinds of mirrors and lenses have which kinds of focal points. She studies up on her optics, sorts out why the focal point of a diverging lens must have a negative value, and memorizes what kinds of optical instruments have what kinds of focal points. All this takes her about ten minutes, after which she vows never again to make a mistake on a question involving optics.

Molly wasn’t content simply to see what the correct answer was and get on with her day; she wanted to see how and why she got the question wrong and what she should have done, or needed to know, in order to get it right. So, she spent a little time studying the question, discovering her mistaken understanding of diverging lenses, and nailing down the principles behind the situation. If Molly were to take that same test again, she definitely would not get that question wrong.

Skeptical readers might say, “But she never will take that test again, and she’ll never see that question again, so wasn’t figuring out her mistake a waste of time?”

No! It’s definitely not a waste of time. Remember that the test is remarkably similar from year to year—both in the topics it covers and in the way it poses questions about those topics. Therefore, when Molly taught herself about optics, she actually learned how to answer similar questions dealing with converging lenses and concave and convex mirrors, which will undoubtedly appear on every future practice test and on the real SAT II Physics.

In studying the results of her practice test, in figuring out exactly why she got her one question wrong and what she should have known and done to get it right, Molly has targeted a weakness and overcome it.

If you take the time to learn why you got a question wrong and to learn the material you need to know to get it right, you’ll probably remember what you learned the next time you’re faced with a similiar question. And chances are excellent that you will be faced with a similar question.

What if you take a practice test and get fifteen questions wrong, and your errors span all the major topics in physics? In that case, you should still do exactly what Molly did: take your test and study it. Identify every question you got wrong, figure out why you got it wrong, and then teach yourself what you should have done to get the question right. If you can’t figure out your error, find someone who can.

A wrong answer identifies a weakness in your test taking, whether that weakness is an unfamiliarity with a particular topic or a tendency to be careless. If you got fifteen questions wrong on a practice test, then each of those fifteen questions identifies a weakness in your ability to take SAT II Physics or your knowledge about the topics on the SAT II Physics Tests. But as you study each question you got wrong, you are actually learning how to answer the very questions that will appear in similar form on the real SAT II Physics. You are discovering your exact weakness in physics and addressing them, and you are learning to understand not just the principles you’re being tested on but also the way that ETS will test you.

True, if you got fifteen questions wrong, studying your first practice test will take time. But if you invest that time and study your practice test properly, you will be eliminating future mistakes. Each successive practice test you take should have fewer errors, meaning you’ll need to spend less time studying those errors. Also, and more important, you’ll be pinpointing what you need to study for the real SAT II Physics, identifying and overcoming your weaknesses, and learning to answer an increasing variety of questions on the specific topics covered by the test. Taking practice tests and studying them will allow you to teach yourself how to recognize and handle whatever SAT II Physics throws at you.