Policy that is in order at most schools:  There is a card to fill out when the child enrolls that identifies the persons who are responsible for picking up the student, and their phone numbers are given.  Most teachers meet with the parents on special occassions such as "Parents Night" or the first day of school to visually identify the persons assigned to pick up the student; I take a cell phone picture at that time.   The school requires that the name of the pick-up person be given in addition to the visual identification. The mandatore teacher's Inservice prior to the school year opening covers this subject in detail.  As a teacher I always asked the student: "Is this Mr.___, or Mrs. ____ as a second verification for a safe transfer of a student from the school to the responsible adult; and I ask them to give me their phone number and sign a form showing the time and day that they picked up my student.   A quick check on my cell phone identifies the phone number and the cell phone picture.   If they do not pass my safe transfer quiz of identification, then I do not hesitate to ask them to provide me proof that they have valad identification and permission to pick up my student. If they are irritated at the time it takes, I always appologize for the inconvenience.  I have been known to call the parent at work to be sure that I release my student to the proper person.  Safety of the student has my top priority.  But, if I know the person that is picking up the student only a friendly greeting is necessary. Usually when I get a call from the office that a person is going to pick up a student from my class, I check on my cell phone their picture and phone number to not delay the transfer when the adult comes to my room.