OP here: he's visiting first grade. i guess, it'd be a summer camp at the schools.

Some schools will allow it and some don't. We visited several schools together. One had us come back and the asst. director spent about 20 minutes with my child alone - it was strange as I specifically asked and thought we were coming back to see how he did in the class. Another, we did a second visit together and the teacher talked to him. Another, which we choose, insisted we leave him for a few hours, we did and it was the winner. I wanted my child to spend some time with the teacher in the classroom to see what was best.

How old is your son?

My son will be doing some private school visits this summer (we just moved here). Some gen ed, some SN schools. A few hours / day visits.
Considering he's been having a lot of transitions lately (moving, different camps/schools), I would imagine it'd be difficult for him to be left at different schools within a period of 2 weeks for his school visits.

How do I know whether the school is a good fit or not? Would it be reasonably to request to stay and see him, even just for the first hour? Or give the teacher one-page of feedback notes?