When you sign up for the test (at least with NUMATS), you can choose to list the school your child attends or not. If you list the school, the scores will be sent to whoever is the contact person with NUMATS. We wanted to share the info with our son's school, and so listed his school, but the results never made it to anyone at the school, at least they didn't make it to his teacher. (We shared the info later.) No one else sees the scores unless you share them.

FYI - Some middle schools around me use Explore scores for part of their admissions process, though I'm sure they are most interested in a kid's 5th grade scores.