Originally posted by: Juno
hehe ACT's easier than SATs.
Whoever told you that is wrong. Some people do better on one, some on another, but most people do about the same. The testing style is slightly different...for example: the math section of the ACT tests a broader range of concepts and requires you to know several formulas, while the SAT has more "trick" questions. I'm an ACT/SAT prep instructor as my side job in college, so I think I speak with some authority.
As for the OP: no sense in taking the ACT until spring of your junior year. Your English and reading skills will grow very much over the next two years. If you've had trigonometry, you will have had everything on the math portion. The more exposure to science and logical thinking, the better. Although most colleges look at your best score, they do see all of them, so wait until you are ready to score your best (spring of junior year and fall of senior year).