There seems to be some confusion about the SAT subject tests. I've now written to several individuals about what they are and who needs to take them. Rather than tell people one at a time, it would make sense to tell a bunch of people at once. The next time someone asks, I can point him to this post.
What are the SAT subject tests and how are they different from the "normal" SAT?
The "normal" SAT was originally designed as an aptitude test as opposed to an achievement test. Because the SAT was designed as an aptitude test, it attempts to measure how well you can solve novel problems - problems that are about what you learned in school, but that are designed differently from the problems you are used to seeing in your homework or on classroom tests. The SAT subject tests are achievement tests. They are designed to measure how well you learned a particular subject. The SAT folks have tests for literature, US History, World History, Math (two levels), Biology, Chemistry, Physics, and nine different foreign languages. The questions on the subject tests are likely to resemble the questions on your classrooms tests.
When and where can you take an SAT subject test?
The SAT subject tests are offered on most of the same dates that the SAT is offered, and will be offered at the same sites. The people taking subject tests will be in a different room from the people taking the "normal" SAT. You cannot take the "normal" SAT and a subject test on the same test date. Registration and payment works just like it does for the SAT, except that the price is different.
You can take up to three subject tests in one morning. You pay for each one. You must register to take a subject test in advance, but you can change your mind about which test(s) to take or even how many tests you wish to take on the morning of the exam. All of the subject tests are in the same test booklet, and if you choose to take multiple subject tests, you can pick which order you wish to take them.
So when would be a good time to take a given subject test? Right after finishing that course would be best. I usually tell students that if they are taking an AP exam in May, they should take the May administration of that subject test as well. You may as well let all of that studying count twice! Students have said that they were well-prepared for the subject test with no additional studying, although one or two pointed out that being familiar with the subject test format is helpful.
Of course, there are AP classes that don't have a corresponding subject test. In addition, the AP Calculus exam and the Math subject tests have hardly anything in common. You would probably be best off taking a math subject test right after completing an honors pre-calculus course.
You should go to the College Board website for details.
Who needs to take an SAT subject test?
Most students do not need to take an SAT subject test. Most colleges don't require them, but if you wish to showcase your kick-ass chemistry skills, most colleges will consider the score as part of your application. Some of the more elite colleges do require subject tests. If you are planning to apply to a selective college, or if you are planning to apply to a very selective program at a less elite college, you should check to see if they require subject tests. The most common requirement would be that you take any two subject tests. However, there are a handful of colleges and programs that require specific subject tests. For example, MIT requires that you take one math test (either level) and one science test. The Honors Program in Medical Education at Northwestern specifically requires the chemistry subject test and the math level 2 test.
What should you do to prepare for a subject test?
The only subject test I tutor for is the math test. You can read what I have to say about preparation here. The information I have on the other tests is hearsay. Students who had taken an AP or IB class in the subject have said that they felt very well prepared without any extra study, although one student did say that she felt she could have done a bit better (over 750 instead of a 730) if she had taken a practice test before the exam. She knew the material, but she had expected the question format to be like the AP test, and the difference put her off a bit. She felt that an hour spent looking at practice questions would have helped.
The College Board has posted sample questions on their website, and have published practice tests which you can order through these link: (Note: the links will not show if you are running adblock)