<p>Speaking as an ACT tutor, the only part of the ACT that you need to be “prepared for” though a high school course is math. Also in my experience, a high-ability student who starts working with me sophomore summer before taking Trigonometry can learn enough trig to get a 30 on math in less than an hour. (They do need good algebra and geometry prep, of course; there’s no quick-and-dirty trick for teaching those.) The algebra and geometry my students get in accelerated 7th and 8th grade math at good private schools is plenty to get them into the 20s.</p>
<p>As for English, Reading, and Science, I find that those are mostly application of skills that students absorbed, or didn’t absorb, throughout their lives, not from high school.</p>