Some schools use SAT subject exams for college credit. GaTech gives credit for college chemistry for instance if a student does well on the Chemistry Subject Exam. Other schools use SAT subject exams to pick scholarship winners, apparently, such as Case Western Reserve University. The subject exam is required by mostly east coast colleges, but since kids that apply to Brown also apply to Harvard, you are competing with students who have taken at least two subject exams. Math 2 and physics are the two easiest exams to score an 800, if you are strong in math and physics. (I think half the test takes in physics score a perfect 800, the test is quite easy if you have had one physics class ) Try the practice exams on line to see if you the material is familiar. They are very easy tests for a well prepared candidate and might as well take them. Then if you end up applying later to schools that require them, you are covered.