Are visits by parents to schools a threat to teaching?

Jay Matthews:

Paula Prosper worried that her son was not ready for the differences between his private Montessori school and the public Fairfax County seventh grade she planned to transfer him to next year.
Prosper, a teacher, asked if he and she could sit for a few hours at Longfellow Middle School “to see what happens in classes and to get a feel for the school in general.” The answer was no, with explanations that made little sense.
Prosper said Longfellow’s director of student services, Gail Bigio, told her “it had to do with privacy issues for the teachers — the public employees whose salaries are paid by my tax dollars. Then she brought up immunization and likened it to the students attending the school who wish to have a visiting cousin shadow them.” Longfellow Principal Carole Kihm told me Bigio did not mention teacher privacy.