If you guys want a good surface to test on, I suggest some clean tile flooring that is in most schools inside. We had a sample of off-brand regolith and compared it to our tile flooring and got similar numbers.
I see no reason why a school wouldn't have tile somewhere.
If it's an issue of "there's other people there", just wait until after they've left and then go use the room. Just make sure to leave it in the same condition you used it in -- wouldn't want to get in some trouble because you messed it all up.
