The are: Math, Reading Comprehension, Science, and English. The first two of these are pretty straightforward. As for the “Science” section, in my opinion it is more or less a reading comprehension exercise on various scientific topics, along with some charts, graphs and numbers that supplement the reading. As for the “English” section, it largely involves questions about grammar and editing. The reading comprehension section provides you with four different reading passages and questions, while the math section tests you on sixty math problems, in ascending order of difficulty, containing questions that run from pre-algebra through trigonometry.
All of the questions on the test—not counting the optional essay—are worth exactly the same. To drive this point home, that means that the easiest question on the test is worth just as much as the hardest question. Considering that you have a limited amount of time to do each section, and considering that all the questions are worth the same amount of points, that means that the typical student should be focusing more on the easier and mid-level questions, and not quite so much on the hardest questions, which typically take much longer to do and are much harder to get right.
When students rush through the easier and mid-level questions, they leave themselves open to making more “careless errors” than they normally would on those questions, and when they get onto the hardest questions, they typically miss them anyway, even with extra time, mainly because those questions are in fact so difficult. You need to keep the following in mind: Cutting down on careless errors is the easiest and best way to improve your test scores. And just how do you cut down on careless errors anyway? Usually, it means slowing down a bit so that you can be more careful and thorough.
The SAT is a multiple-choice test. As with all multiple-choice tests, you should be using the process of elimination (or POE for short) as your main method of attacking these question, especially on the English, reading comprehension, and science sections.