Ghost did PLUS at 10 years old in 5th grade. No prep other than going through the booklet to see what is the test format.
He did SAT at 11 in 6th grade. Again, prep involved going through the official SAT booklet to find out about different types of questions and he was checking online for "SAT question of the day".
This year,at 12 in 7th grade, he will repeat SAT and write ACT.
He does have an Official SAT Study Guide now and is looking at math questions. ACT prep will include looking through the booklet. He is participating in a talent search most likely for the last time.
My daughter, 10 years old in 5th grade, will write an Explore. I would love to get my hands on some kind of a booklet so she wil know what types of questions to expect!