A conscientious couple wanted to send their child to the Arlington Traditional School, a public magnet famous for having everyone reading by the end of kindergarten. They took the standard tour but yearned for more. Could they sit quietly in one of the classes for an hour or so, they asked, to get a better sense of the place?

Absolutely not, school officials told them.

Another couple applied for admission to a popular private preschool. During that school’s tour they saw one child hitting another without any staff intervening. They called later, asking if they could sit in on a class for an hour or so just to satisfy them that what they had witnessed was an anomaly.

Forget about it, the school director said. In fact, she added, she was so troubled by their attitude that she was tearing up their application.

Schools are often defensive and unhelpful to the parents of their students . Until I learned the stories of these two couples, I hadn’t considered that parents of children not even enrolled can get the same cold shoulder. The private school director’s sharp response is common to that breed. She had all the power and no need to cater to outsiders.

But Arlington’s stiff attitude about applicant parents observing classes is a surprise to me. The county has some of the smartest school board members, superintendents and teachers I have encountered anywhere, and a solid national reputation. What does it have to fear from young parents soaking up the warm, lively atmosphere of its classrooms?

I suspect many other schools, public and private, have the same knee-jerk restrictions on outsiders hanging around a classroom to feel the vibe. I am wondering how they know this would cause trouble if they have never allowed it.

Arlington’s rules allow parents to observe for an hour or so classes in which their children are enrolled, but for applicant parents (whose need to know seems to me greater), the standard tour is all they are going to get.

Arlington schools spokeswoman Linda Erdos gave this explanation: “ATS does a parent orientation for the school eight times during the school year before the April 15 deadline. The orientations are approximately 90 minutes in length. During that session, the principal takes parents through the school with stops in all the common use areas — library/media center, art, music, PE and other special service areas.” She also takes them through all of the classes, and allows 10 minutes in one of the kindergarten classes.

Parents can come back, but only to join another of the scheduled orientation tours. Why not let them sit for an hour in a classroom? Erdos’s reply: “In total,” she said, “approximately 250 to 300 families (sometimes one parent, sometimes both) visit ATS during these sessions. Providing customized, one-on-one meetings for each family would be an added disruption to the school and the classroom setting.”

I wasn’t asking about 250 people. It was just one couple who wanted to do this. It would give them no advantage in the selection process, which is by random lottery. Arlington hasn’t tried to accommodate these rare requests, so officials don’t know how distracting the practice would be. Erdos said they would allow parents of students just admitted to make such a visit, if anyone asked.

Erdos has never told me I could only sit in a classroom I was writing about for 10 minutes. Is a reporter looking for details that might become a few dozen words in a story more important than parents who want to put their child in the school?

As teachers and parents have been explaining to me for decades, schools are full of rules that make no sense. Arlington Traditional and other places that bar parents from listening and watching might rethink that taboo before more nice people attracted by their great reputations start visiting again this year.