My son took SCAT in second grade. He loved taking it! (I'm not sure why, LOL). There were alot of other middle-aged men taking some kind of graduate engineering test at the same time, so it might be good to explain that other adults will be there. My son was the only kid there.
You also might want to explain what it's like to take an online computer exam. My son had never did that before either.
The center had a chair that didn't spin around, which I think is a good idea. They gave him a little foot rest since his legs were obviously too short to touch the ground!
