My son took the Explore test yesterday morning. It is the 8th grade test by the ACT developers. This test measures academic achievement (rather than aptitude). DS is 10yrs 4months and in 5th grade. He qualified and will be evaluated as a 5th grader (instead of by age).
This was the first time that I signed him up (it was not initiated through school). He enjoyed it and was not overly frustrated although he knew he did not get all the answers right.
There were approximately 50 participates in a school cafeteria. His advice to those taking it in two weeks is to BRING A WATCH. He found it very helpful as he could not see the wall clock from his seat!