DS did take the ACT in 6th grade, had not taken the Explore. I think if you take it through a talent search, the writing portion is not included anyway. To prepare, well, does she do testing in school already? That's a good start. Also, get the booklet from ACT or a prep book from your public library. Take the sample tests (we set up at the dining room table a couple of Saturday mornings and did one portion of the test each Saturday, with a timer.) Then grade the test and for any incorrects, figure out if it's an error in knowledge, a Mis-mark, a timing issue, or (as DS figured out) an error in the book.
Then, if you want to, go through the prep sections. But it's interesting to take the practice tests first. We found that the score on the practice test was predictive of the actual one. That was true of my HS junior, too.
