Hi,
My fifth grader took the Explore in January through TIP. The only prepping she did was to do the practice test that came with our registration pack. I would say its mostly to see ability and how they interpret data. If your child has experience with standardized testing I wouldn't worry. If not, then work on using a bubble sheet and transferring answers from the book to the answer sheet just to get comfortable. Overall it was a good experience for DD.
Wendy